Java Edition:Item Duplication Methods

Item duplication methods are bugs that allow for an item to be duplicated, creating a limitless amount of that item. Many methods are generic and allow for any item to be duplicated, but some only work for specific items.

Why a Discontinued Feature?

Item duplication can create discontinued features because it allows for more nonrenewable resources to be obtained than normally possible. Nonrenewable resources are the items that exist in only a limited amount in each world. The main cause of nonrenewable items is that they can only be created from world generation, but some other examples, such as the dragon egg, are due to other reasons. The dragon egg is the most extreme example because there should only be one per world dropped from the very first ender dragon killed in a world. The dragon egg quantity of a world can exceed this limit using duplication.

Generic Item Duplication Methods

Understacked Items

From Indev 0.31 20100124-2310 to 1.10.2, understacked items were obtainable through various methods. Understacked items can be used to duplicate their item in several ways, due to many checks in the game not expecting negative item counts and allowing the understacked item to be decremented infinitely.

Player and Chunk Save Desync (Alt + F4, Task Manager, etc.)

From Infdev 20100327 to 25w42a (present), there is a collection of methods that rely on the fact that the game saves the player and chunks at separate times, so forcing the game to stop can cause a desync between these saving processes and cause item duplication.^[1]

Normal Close

From Infdev 20100327 to 12w26a (a 1.3.1 snapshot), the game will immediately stop when its window is closed and perform no additional actions. The autosave functionality would periodically save the player's data and a limited amount of chunks marked to be saved. By removing items from a chunk and waiting for an autosave to save the player's data, if the chunk that was modified was not part of the limited amount of chunks to be saved the items would be saved to disk both in the chunk and in the player's inventory. At this point, the game can be closed to ensure the modified chunk is not written to disk. Rejoining the world will reload the player and chunk from disk, duplicating the items.

In singleplayer from Infdev 20100327 to Beta 1.5_01, chunks save in ascending order of their hash value, calculated as (chunkX & 31) + (chunkZ & 31) * 32. This will be a value from 0 to 1023. In singleplayer from Beta 1.6 Test Build 3 to 12w17a, chunks save in the order they were loaded in. In dedicated and integrated servers from Alpha server 0.1.0 to 1.9^[test], chunks save in the order they were loaded in. Players will load their chunks in a north west to south east fashion before 1.9. After 1.9, they will load in the order of which is closest to the player. From 1.10 to 25w42a (present), chunks save in ascending order of their hash value, calculated as x & 4294967295L | (z & 4294967295L) << 32. This will be a signed 64 bit integer value.

The player may need to mark chunks earlier in the unload sequence to be saved to allow the desired chunk to be skipped. The easiest ways to mark large amounts of chunks to be saved is by placing entities in them, as any chunk with an entity present will be marked to save. Most normal worlds have large numbers of chunks with entities present, increasing the chances of this method working. Toggling large redstone lines is an alternative option to mark many chunks to be saved.

An autosave can be manually triggered in singleplayer from Infdev 20100629 to 12w17a and from 12w22a to 25w42a (present) by pressing Esc to access the ingame menu. An autosave can be manually triggered on dedicated servers from Alpha server 0.1.2 to 25w42a (present) if either the console or players with operator privileges runs the /save-all command.

Beta 1.9 Prerelease introduced a separate thread to handle reading and writing files to disk. Previously, all file operations were handled on the main game thread. The chunk saving order is still preserved, but versions with multiple file I/O threads can save multiple chunks at once. This can allow slowing down the saving process for chunks that are selected to save to such a point that they are never written to disk. In versions where all chunks are saved upon an autosave, duplication succeeding becomes a race condition between the main thread closing the game and the I/O thread saving the chunk to disk. The slower the I/O thread runs and the later a chunk is scheduled to be saved to disk, the higher the chance of the chunk not saving is. The I/O thread can be slowed in a number of ways:^[2]

• Place large amounts of data into loaded chunks to increase the time needed to serialize and write them to disk (e.g. using written books)
• Running the game on a processor with poor parallel performance (some operating systems such as Windows allow restricting which cores a program may run on which can emulate this effect)
• Storing the world on a disk device with poor I/O speeds (e.g. a hard disk drive)
• Running large file operations on the disk that stores the world to keep the disk busy
• Increasing render distance to load more chunks to increase the work the IO thread must do

Normal Close (Singleplayer Only)

From 12w27a (a 1.3.1 snapshot) to 18w43c (a 1.14 snapshot), the client has a faulty runtime shutdown hook. A shutdown hook is registered that causes the game to save the player and the world to disk. However, this hook is never called on the client as a function that is called when the window requests to be closed calls System.exit(0);, which immediately closes the Java runtime without calling the shutdown hook, resulting in the player and world not being saved when the game closes. For servers, methods of closing the game that do not instantly stop the Java process will succeed in this shutdown hook triggering (e.g. pressing CTRL+C in a console or closing the server GUI window). For versions with multithreaded I/O, this will discard any actions queued for I/O, potentially allowing chunks to never be saved. This bug allows methods detailed in the previous section to continue to work in singleplayer until 18w44a, where the shutdown hook was fixed to correctly save the player and world.

Force Kill

From Indev 20100327 to 25w42a (present), the game will try to save any unloaded chunks to disk as they unload regardless of the autosave process. This can be abused by force killing the game process to prevent any other chunks or the player's data from saving, allowing for duplication. To duplicate items, place the items to duplicate in the player's inventory. Ensure the player's data is saved by relogging. Place the items into a chunk, and then unload that chunk. Wait for that chunk to save, and before an autosave saves the player's data, forcibly terminate the game process.

• For any computer, disconnecting the power will terminate all program execution.
• For Windows 10/11, open Task Manager, find the game process, right click and select "Go to details". This will highlight the game process in the "Details" tab. Click the "End task" button, and confirm by clicking "End process".
• For Linux, use the kill -9 <pid> command or otherwise to send the SIGKILL signal to the game process.

If the modified chunks save before the process is terminated, the items will be saved to disk in both the modified chunks and the player's inventory, duplicating the items. This is most easily performed by using a Nether or End portal to quickly change dimensions, unloading all chunks around the player (except spawn chunks, of course).

Autosave Intervals

Below are the autosave intervals of clients and servers, and the maximum amount of chunks each autosave can save.

Pre-Integrated Server Clients

Version Range	Autosave Interval	Max Number of Chunks Saved
Infdev 20100327 to Infdev 20100415	200 ticks (10 seconds)	10
Infdev 20100420 to Infdev 20100618	100 ticks (5 seconds)	2
Infdev 20100624 to Alpha v1.0.15	20 ticks (1 second)	2
Alpha v1.0.16 to Alpha v1.0.17_02	4 ticks	2
Alpha v1.0.17_03 to Beta 1.5_01	40 ticks (2 seconds)	2
Beta 1.6 Test Build 3[test] to 12w17a (a 1.3.1 snapshot)	40 ticks (2 seconds)	24

Integrated Server Clients and Servers

Version Range	Autosave Interval	Max Number of Chunks Saved
Alpha server 0.1.0	20 ticks (1 seconds)	2
Alpha server 0.1.1 to Alpha server 0.1.4	4 ticks	2
Alpha server 0.2.0 to Alpha server 0.2.5_02	40 ticks (2 seconds)	2
Alpha server 0.2.6 to Alpha server 0.2.8	40 ticks (2 seconds)	32
Beta 1.0 to 12w24a (a 1.3.1 snapshot)	40 ticks (2 seconds)	24
12w25a (a 1.3.1 snapshot) to 12w26a	100 ticks (5 seconds)	unlimited
12w27a (a 1.3.1 snapshot) to 1.14 Pre-Release 1	900 ticks (45 seconds)	unlimited
1.14 Pre-Release 2 to 25w42a (present)	6000 ticks (5 minutes)	unlimited

Failed Block Entity Save

In Infdev 20100327, chests and other block entities do not save changes to their contents unless the chunk is marked to be saved. Examples of things that mark a chunk to be saved are breaking or placing blocks, or changing light levels from placing light sources. This version does not save if a chunk has been populated, so every time a chunk is reloaded it will populate, which may change blocks in the chunk and mark it as modified. This version also will mark any chunk containing a block entity to be saved upon first loading, so the player must wait for chunks to save after loading to unmark them for saving. The game will unload 10 chunks marked to be saved every 10 seconds (200 ticks), so the longer the player waits the more likely it is for any chunk to be saved and unmarked for saving. To duplicate items, place the items into a chest or other container. Mark the chunk to be saved and wait for it to save (saving and quitting will save all chunks in the world to disk). Reload the chunk and wait at least 10 seconds for the chunk to be unmarked for saving. After the chunk is unmarked for saving, take the items out of the container without otherwise updating the chunk and reload the chunk (e.g. by saving and quitting). The items will save in the player's inventory, but the container will not save, duplicating the contents.

Unloaded Minecart GUI Reference

In Infdev 20100618, minecarts were used as containers, essentially being an early version of the chest minecart. By opening the minecart's inventory and moving the minecart out of the players render distance while it is open, the cart's contents would be saved to disk, but the player would retain a reference to the unloaded items in the open GUI. Removing the items from the GUI does not update the saved contents, duplicating the items.

Client Chest Desync

From Alpha server 0.2.0 to Alpha server 0.2.8, it is possible to abuse the client sided inventory to duplicate items on dedicated servers. This method is easier to perform the laggier the connection to the server is. Prepare the item to dupe in the cursor, then place it into the chest and take it out. This will send two packets to the client, one telling the client to put that item into the chest and another to remove the item. If the timing works, the item should briefly reappear in the chest due to the latency from the first chest update packet being sent to the client. The player must quickly take this item out of the chest, as it will soon be removed by the second chest update packet. Placing items into the chest before the chest update packets are received can result in item deletion.

Chunk Savestating

From Beta 1.3 to 25w42a (present), there are numerous ways to savestate a chunk. Savestating a chunk prevents the chunk from saving any updates to its contents to disk, so when it is reloaded the game will use the last successfully saved state of that chunk. To duplicate items, place the items to duplicate in a chunk and save the chunk. Savestate the chunk, take the items out of the chunk, and reload the chunk. The items will reappear as they last were saved, duplicating them. This method also works with any entity, although there may be issues as they will have duplicate UUIDs.

Ender Pearl Disconnect

From Beta 1.9 Prerelease 2 to 12w24a (a 1.3 snapshot), there is a multiplayer exclusive method of duplication utilizing thrown ender pearls. Ender pearls would store a direct reference to the player that threw them. To perform this method, collect the items to be duplicated in the player's inventory. Ensure the player has less than 3 full hearts. Less may be necessary if the player has armor with Protection or Feather Falling equipped. Throw the ender pearl and log off before it lands. This will save the player's inventory. If the chunks containing the pearl are still loaded, such as by another player or by being in spawn chunks, the pearl will continue to fall and land, dealing 6 fall damage to the stored player reference, dropping their inventory where the pearl landed, duplicating the items in the player's inventory.

Loading Currently Saving Chunk

From Beta 1.9 Prerelease to 1.13^[test], if a chunk attempted to load while the game was currently saving it to disk, the game would load the outdated version saved to disk instead of the version currently being saved.^[3] This can result in numerous duplications and deletions across chunk borders, such as with pistons pushing or pulling blocks, entities moving, or a hopper clock running. To reliably duplicate items with this method, hoppers are used, which are available in 13w01a (a 1.5 snapshot) and above. To perform this method, aim two hoppers split by a chunk border at one another so items inside are passed back and forth. Walk in the direction of the chunk border the hoppers pass through and walk a number of chunks away equal to the world render distance minus one (such that both hoppers are still loaded by the player, but walking across another chunk border will unload one of the hoppers, not both!). Create a powered rail line that is 10 blocks long with 5 blocks on each side of the next chunk border. Relog at one end of the rail to sync the player's chunk loading position. Place and ride a minecart. This will continually unload and reload the chunk containing the hoppers, which eventually will lead to item duplication. Do not perform this method within spawn chunks.

The I/O thread can be slowed in a number of ways to increase the chances of winning the race condition. These include:

• Place large amounts of data into the chunk continually being unloaded and reloaded to increase the time needed to serialize and write it to disk (e.g. using written books)
• Running the game on a processor with poor parallel performance (some operating systems such as Windows allow restricting which cores a program may run on which can emulate this effect)
• Storing the world on a disk device with poor I/O speeds (e.g. a hard disk drive)
• Running large file operations on the disk that stores the world to keep the disk busy

LAN Player Data Duplication (Singleplayer Only)

From 12w24a to 25w42a (present), the LAN server feature can be used to duplicate player data as the server stores player data in both the level.dat file and a separate player data file unique to each player's username or UUID. The singleplayer player data will always try to load the data stored in level.dat first regardless of the contents of the separate player data file, so switching users can duplicate the singleplayer data to any number of separate player data files. This method requires either two accounts or using a launcher that allows running the game in offline mode with any username, such as MultiMC (in other words, a "cracked" launcher). To perform this method, launch the game with the first account. Put any items to duplicate in the first account's inventory and save and quit the world. Launch the game with the second account, and open the world. Open the world to LAN, and join the LAN server with the first account. Both players now have the same inventory. Remove the items from the first account's inventory, then save and quit the world. Launch the game with the first account, and reopen the world.

Update Suppression

From 12w34b to 25w42a (present), update suppression can duplicate any item by suppressing its placement into an item frame. Note that attempting this in some versions will cause the game to crash, possibly causing corruption. See the update suppression general information for how to avoid this.

Hopper Outdated Block Entity

From 13w01a (a 1.5 snapshot) to 1.12.1, if a chunk containing block entities was unloaded and reloaded in the same game tick, the block entities within the chunk would be duplicated for one game tick as the game ticks removed block entities once before removing them.^[4] If one of those block entities is a hopper that also had its cooldown timer expire on that same game tick, two items would be moved as each of the duplicated hopper block entities would move an item. To perform this method, aim two hoppers at one another so items inside are passed back and forth. Place a hopper facing into the border of the chunk that contains the two hoppers and put an item into it (it should not be inside the chunk that contains the two hoppers, as this hopper needs to continually attempt to reload the chunk containing them every game tick). Walk in the direction of the third hopper a number of chunks away from the chunk containing the two hoppers equal to the world render distance. Create a powered rail line that is 10 blocks long with 5 blocks on each side of the next chunk border. Relog at one end of the rail to sync the player's chunk loading position. Place and ride a minecart. This will continually unload the chunk containing the hoppers, which combined with the hopper reloading the chunk every tick will eventually lead to item duplication. Do not perform this method within spawn chunks.

Hopper Item Entity Pickup

In 13w01b (a 1.5 snapshot), the hopper did not properly remove item entities upon picking them up, resulting in being able to pick up the same item multiple times.^[5] The easiest method is to place a slab on top of the hopper and drop the item to be duplicated on the slab. If the stack is not at the max stack size, it will be picked up twice, duplicating the items. If the stack is a full stack, the hopper will duplicate the item stack every time it attempts to pick the item entity up infinitely. The most recent item stack to be duplicated will be a shadowed item stack shared with the item entity. Picking up the item entity will make the shadowed stack a zero stack.

Donkey, Mule, and Llama Duplication

LAN and Multiplayer Relog

From 13w19a to 13w25c (1.6.1 snapshots), relogging while the world was open to LAN or on a dedicated server while riding a horse, donkey, or mule would duplicate the entity.^[6]

Unloaded GUI Reference (Multiplayer Only)

From 13w19a (a 1.6.1 snapshot) to 1.6.1 and from 19w08a (a 1.14 snapshot) to 20w16a (a 1.16 snapshot), it is possible to retain the GUI of a donkey, mule, or llama when another player logs out while riding one. If a player shift-right-clicks a donkey, mule, or llama with a chest that is not already ridden by a player, they will open the GUI. A second player must mount the mob and then log out. This will save the mob's inventory along with the player's data, but the first player will retain a reference to the GUI and all items it contained, duplicating the items. When the second player reconnects, the mob will have all items it previously had.

Piston Item Frame Destruction

From 13w36a (a 1.7.2 snapshot) to 18w22b (a 1.13 snapshot), if an item frame was moved by a piston (e.g. piston head extends into it) on the same tick a player removed the item from the frame, the item would be duplicated.^[7] To perform this method, place an item frame on a wall, and insert the item to be duplicated. Place a piston facing into the block the item frame occupies. Set a button on a predictable delay with redstone repeaters to power the piston (e.g. use three repeaters, two on full delay and one on half delay for a one second delay). Press the button to power the piston, wait one second, and then attack the item frame. If the player's timing is successful, the item will drop twice, duplicating it. Creating a macro to perform the timings automatically and predictably may be desirable.

Disconnection of Shadowed Item Stack

From 14w21a (a 1.8 snapshot) to 1.19 Deep Dark Experimental Snapshot 1, update suppression could be used to duplicate references to the same item stack, also known as item shadowing. Shadowed items can allow for duplication in various ways. The easiest method is to unload shadowed items, as the game will save all instances as if they were separate items, duplicating the shadowed item stack.

Hopper and Chest Minecart Duplication

From 15w39a to 15w39c (1.9 snapshots), unloading a hopper minecart or chest minecart and reloading it would cause its items to be dropped, but the minecart's contents remain. This is due to a duplicate UUID bug and it may take at least one unload for the minecarts to have duplicate UUIDs.

Removed Shulker Box GUI Reference (Multiplayer Only)

From 16w39a (a 1.11 snapshot) to 1.19, shulker boxes destroyed directly in the processing of a packet can have their contents accessed on the same game tick as they are destroyed. If the contents are changed after the shulker box is dropped as an item, the contents are duplicated between the GUI and the dropped shulker box. To perform this method, two players are needed. Place the item to be duplicated inside a shulker box. The first player must perform an action to destroy the shulker box by either mining the box or exploding the box with an end crystal by directly attacking the crystal. The second player accesses the shulker box to remove an item at the same time the first player destroys the shulker box. If the two actions are performed on the same server game tick with the first player's action being processed first, the item the second player removes will be duplicated.

This method can duplicate every item except for shulker boxes, as they cannot be inserted into themselves.

This method may be performed with only a single player, but requires a modified client to allow a single player to destroy and access the shulker box at the same time.

Elytra Firework Death (Multiplayer Only)

From 16w50a (a 1.11.1 snapshot) to 20w51a (a 1.17 snapshot), the player can die and drop their inventory after logging out when flying with an elytra and boosting with a firework rocket that deals damage when it explodes. As the player's inventory saves to disk upon logging out, the player will log back in with their inventory, duplicating its contents.

Recipe Book Overstacking

From 17w17a (a 1.12 snapshot) to 1.12, the recipe book could duplicate and overstack any item due to a bug. The method worked by dropping the item desired to be duplicated then spamming the autofill recipe in the recipe book.

Zombie Conversion

From 18w11a (a 1.13 snapshot) to 1.14.3, killing a zombie in the same tick that it converts into a drowned (also works when a husk converts into a zombie) will both convert the zombie and drop the items they were holding. As zombies have a chance to be able to pick up any item, including shulker boxes, any item can be duplicated. From 18w11a to 19w09a (a 1.14 snapshot), the zombie can convert at any point during the death animation instead of only on the same game tick as it is killed, giving a much more lenient time window of 20 ticks (1 second).

Design for 18w11a to 19w09a:

Design for 19w11a to 1.14.3:

Baby Piglin

From 20w09a (a 1.16 snapshot) to 1.16.2, baby piglins that were killed while observing a piglin loved item would drop two of any item they were holding.^[8] To perform this method damage a baby piglin such that it can be killed in a single hit. Give a baby piglin any item first, and then give the baby piglin a piglin loved item. While the baby piglin is observing the loved item, kill the piglin. The item will drop twice, duplicating it.

List of Piglin Loved Items
Bell
Block of Gold
Block of Raw Gold
Clock
Deepslate Gold Ore
Enchanted Golden Apple
Gilded Blackstone
Glistering Melon Slice
Gold Ingot
Gold Ore
Golden Apple
Golden Axe
Golden Boots
Golden Carrot
Golden Chestplate
Golden Helmet
Golden Hoe
Golden Horse Armor
Golden Leggings
Golden Pickaxe
Golden Shovel
Golden Sword
Light Weighted Pressure Plate
Nether Gold Ore
Raw Gold

Unloaded Ridable Entity GUI Reference (Multiplayer Only)

From 20w17a (a 1.16 snapshot) to 1.19, rideable entities that have a GUI that are removed from the world by a player logging off while riding them can have their contents accessed on the same game tick as they are removed. If the contents are changed after the entity has been removed and saved to disk with the player who logged out riding them, the contents are duplicated between the GUI and the logged off entity. To perform this method, two players are needed. The first player must ride an entity with a GUI, such as a donkey, mule, or boat with chest. Place the item to be duplicated inside. The second player accesses the entity's GUI to remove an item at the same time the first player logs out. If the two actions are performed on the same server game tick with the first player's action being processed first, the item the second player removes will be duplicated.

Dolphin Nether Portal Pickup

From 20w28a (a 1.16.2 snapshot) to 1.17 Pre-release 1, if a dolphin picks up an item in the same game tick as it travels through a Nether portal, the item will duplicate as the removed dolphin will drop the item after duplicating itself to the target dimension.^[9] Note that sometimes the items go through the Nether portal.

Overstacked Bundles

Overstacked bundles allow for item duplication. To duplicate items with overstacked bundles, place the items to be duplicated into the overstacked bundles, and separate the bundles into individual items. Each separate bundle will now contain a copy of the items inserted. This method works from 20w45a to 25w42a (present), although overstacked bundles are not available in all versions in this range. See the main page for more information on obtaining overstacked bundles.

These bundles may also be used to duplicate themselves. At least 2 overstacked stacks of bundles are needed. One must be 2 to 15 bundles, as if a bundle contains 16 nested bundles it cannot be nested again, which is necessary for this process. Place the stack of 2 to 15 bundles into another single bundle. Use the second overstacked stack of bundles to duplicate the bundle containing overstacked bundles. As long as the player has at least 2 bundles containing overstacked bundles, the player can remove one of the overstacked bundle stacks, place the bundle containing more overstacks inside, and unstack them to create more bundles containing overstacked bundles.

Bundle Crafting Ingredient Duplication

From 20w45a to 20w46a (1.17 snapshots), bundles could be used to remove the ingredients in a crafting grid without updating the crafting output.^[10] To perform this method, place a recipe to craft in a crafting grid such that an item is present in the crafting output slot. Pick a bundle up with the cursor, and left click on the ingredients to remove them from the crafting grid. The output then can be removed, duplicating the ingredients. Dyeing shulker boxes allows for duplicating any item.

Bundle or Shulker Box Destruction

20w51a (a 1.17 snapshot) added the mechanic that when a bundle or shulker box item entity was destroyed, all of the items inside of it would be dropped. However, if the item collided with multiple block damage sources in the same tick that it was destroyed, the items would drop for each damage source.^[11][12]

The easiest method is to drop a bundle or shulker box into a lava cauldron, as due to a separate bug lava cauldrons apply damage twice. Placing a trapdoor or similar above the cauldron may be desirable to better align items as they are dropped in. Standing directly next to the lava cauldron should allow for the player to pick up items before they can burn, but the player should ensure they have enough space in their inventory to pick up all of the duplicated items.

Another alternative is to drop the bundle or shulker box between two or more fire blocks, lava blocks, or even cacti. The player should align themselves such that they are directly in the middle of the damaging blocks such that the dropped item collides with all blocks' hitboxes.

As most methods use fire to damage the items, netherite is much easier to duplicate due to being fireproof.

Anvil Dupe

From 1.17 Pre-release 1 to 1.17, if an anvil breaks when the player takes the result item and the player's inventory is completely full (unable to pick up the result item), the result item will drop twice, duplicating it. To perform this method, place the item to duplicate into the first slot of the anvil screen. Fill the player's entire inventory with items such that there are no empty slots. Rename the item until the anvil breaks.

At a 12% chance to take damage on each use, it takes on average 8.33 anvil operations to damage an anvil by one damage level. Anvils can also be pre-damaged to the "Damaged Anvil" state (the last state before breaking) by dropping them as falling blocks. After dropping at least 20 blocks, the anvil is guaranteed to be damaged by one damage level. Falling anvils will not be damaged by more than one damage level per fall.

Allay Nether Portal Pickup

From 22w18a (a 1.19 snapshot) to 1.19.1 Pre-release 6, if an allay picks up an item in the same game tick as it travels through a Nether portal, the item will duplicate as the removed allay will drop the item after duplicating itself to the target dimension. Note that sometimes the items go through the Nether portal.

minecraft:dupe_hack Item

In the April Fools' version 23w13a_or_b, the minecraft:dupe_hack item can be used to duplicate items. This intentional feature is obtainable by enabling the "Set chance of dupe hack occurring to <NUMBER>%" (dupe_hack_occurrence_chance) vote and killing an entity with a chest. The dupe hack item will occasionally drop. These include minecarts with chests, donkeys, mules, llamas, and boats with chests. To duplicate an item, craft it together with a dupe hack item.

Crafting Table Ingredient Removal Fail

In 24w18a (a 1.21 snapshot), the ingredients placed in a crafting grid sometimes will not be removed upon crafting an item.^[13] To duplicate any item, place the items inside a shulker box. Dye the shulker box by placing the shulker box and a dye item into either the bottom row for a 2x2 grid or the middle row for a 3x3 grid. The ingredients will not be removed upon crafting the dyed shulker box. To craft another, pick up and place back one of the ingredients to update the crafting output slot.

Shulker Box Break

In 25w02a (a 1.21.5 snapshot), shulker boxes will both drop a shulker box with its contents and drop their contents as item entities when broken with either a piston or when blown up by an explosion.^[14]

Specific Item Duplication Methods

Door

From Infdev 20100607 to Beta 1.5_01, if an update is generated when placing a door and this update updates the top of the door, the doors will be duplicated (Similar to Java_Edition:Half_Door_(Block) method).

Bed

Since the first addition of beds in Beta 1.3 to Beta 1.9 pre 5 and 14w03a (snapshot 1.8) - 16w40a (snapshot 1.11), if a bed causes an update when placed that changes the state or position of a neighboring block, and this update touches the top of the bed, the beds will be duplicated (Similar to the Java_Edition:Half_Bed_(Block) method).

Amethyst

In 20w45a moving an amethyst cluster on slime blocks will drop amethyst shards but keep the clusters on the slime blocks.

Barrel

From 21w11a to 21w13a, when taking items out of a barrel right before TNT blows it up, then it will drop as an item and be harvestable as well, resulting in x2 duplication.^[15].

Candle

From 20w45a to 20w49a (1.17 snapshots) right-clicking a cake that has a candle on it while having full hunger will dupe the candle.^[16]

• 

  Candle duplication from a cake being right-clicked

Crimson & Warped Door

In 20w06a (1.16 snapshot), the new crimson and warped doors would drop two items when broken.^[17] Fast farms for their duplication could be created by placing the doors onto trapdoors that were on a 1 tick clock that continually opened the trapdoors and broke the doors on top.

Double Plants

In 14w25a - 1.8^[18] and also later in 17w47a (1.13 Snapshot),^[19] removing the block a double plant is on would drop 2, duplicating it^[20]

or in 17w47a only, by breaking them with a piston.

• 

  (1.8) A simple machine that removes the soil breaking the plant once placed.
• 

  (17w47a) A simple machine that breaks the plant once placed.

Honey Bottles

When bee's nest and hives were first added in 19w34a and 19w35a (1.15 Snapshots) dispensers would ignore the honey level and always dispense honey bottles.^[21]

Items with Block Forms

In 13w01a (1.5 snapshot), you can duplicate minerals by placing some of them into a crafting table along with the associated mineral block and picking up one of the minerals and double clicking the mineral into your inventory. This should result in you have 9 more than you started. The glitch can be preformed with iron, gold, diamonds, emeralds, and redstone.^[22]

Iron And Oak Doors

In 14w02a to 14w02c (1.8 snapshots) placing a door under a redstone torch or piston head will duplicate the door.^[23] The redstone torch will not drop but the piston will, allowing it to be done renewably.

Note: Placing a door under the piston base will crash the game.

Melon and Pumpkin Seeds

In 17w47a and 17w47b (1.13 Snapshots) you can get melon and pumpkin stems on grass or dirt^[24] and whenever they grow their plant the stem will break but will still stay attached, whenever they break they will drop their seeds like normal, this works from 17w47a to 25w42a (present).

• 

  Melon and pumpkin on dirt and grass

Multi-blocks

In 1.16 Pre-release 4 manually breaking the bottom of a door, bottom of 2 tall plants and or destroying the head of a bed would drop an extra block.^[25]

This can only be done manually, water, explosions and or pistons does not work.

Pointed Dripstone

^{[26] [27]}

Potted Plants

From 13w32a - 1.7.2 breaking a flower pot by removing the block under it would duplicate the plant inside of it^[28]

Rails

From Beta 1.7 - Beta 1.7.2 pushing a rail off a block with a 0/1-ticking a sticky piston would duplicate it.

Rails and Carpets

From 1.12.2 to 25w42a (present) rails and carpet can be duped with a simple piston machine. There are slight differences between versions.

• 

  Machines used to dupe rails(left) and carpet(right) in 1.12.2

Redstone Dust

In 14w25a and 14w25b (1.8 Snapshots) redstone dust can be duplicated by placing it next to power and then removing the block below it downwards^[29]

• 

  A super simple setup by tbuckleyc

Shield

In 20w07a and 20w08a giving a piglin a shield and then killing it results in it dropping 2 shields.^[30]

Shulker Box

In 17w18a, placing shulker box underneath the lever or button duplicates the shulker (you are left with empty shulker box in your inventory).^[31] This does not duplicate contents of the shulker box.

String

From 14w25a to 1.8-pre3 string could be duped with simple slime block contraption.

Tipped Arrows

In 15w31a, shooting any tipped arrow (except "Water Bottle" arrow and spectral arrow) while having more of the same type of arrow in the inventory and than picking it up from the ground will duplicate the arrow.^[32] Shooting "Water Bottle" arrow will consume the arrow and after picking it up, you will obtain regular arrow instead of "Water Bottle" arrow.^[33]

Trapdoor

Iron or wooden trapdoors pop off as items when powered in 14w25a (1.8 snapshot).^[34] They are often destroyed by redstone power but will drop two items in that case. Occasionally^[test], a trapdoor will be resistant to breaking and therefore can be used for quicker duplication by powering it with a clock/lever rapidly.

Tripwire Hook

From 1.15.2 to 1.18.1 (present) ^[test], placing at least two tripwire hooks on opened trapdoors facing each other, string between them and stepping on the string will dupe tripwire hook facing east or north. ^[35]

Torch

From 1.10-pre1 to 1.15-pre4 relogging in the end during the initial fight would reset the ender dragon and the exit portal.

Until 17w47a (1.13 Snapshot) you would have to break each torch on the exit portal before relogging but after 17w47a it would always duplicate the south and east torches, though north and west would still need to be manually broken.^[36]

Lead

Bees

From 19w34a to 19w35a (1.15 snapshots), the bug allowing beehives with a leashed bee can be used to duplicate leads.^[37] When the leashed bee enters the beehive/bee nest the lead will pop off but when it comes out the bee will still be leashed to the player and so once that is broken the player will have two leads.

End Portal

From 14w31a (1.8 snapshot) to 19w04a (1.14 snapshot), all leashed mobs that would go through end portal will drop two leads upon entering different dimension instead of one.^[38] This method works with all leashable mobs and it works when entering/leaving end.

Wither Skeleton Skull

In 18w30b, placing wither skeleton skull crashes the game and it fails to place.^[39] However placing it with dispenser crashes the game but dispenses invisible wither skeleton skull with outline. This doesn't consume wither skeleton skull in dispenser but breaking dispensed wither skeleton skull drops nothing, however placing hopper under it or changing versions makes it normal, so breaking it actually drops.^[40]

Any Craftable Item

Double Click Quick Grab

In 13w01a, the double left click quick grab inventory movement mechanic could grab items from the output slot of crafting.^[41] This will pick up the item from the crafting output slot without removing the ingredients, creating the resulting item for free. To perform this method, obtain at least one of the item to be duplicated. Place the items necessary to craft the item into a crafting grid such that the item to be duplicated appears in the crafting output slot. Double left click the item you already obtained. To repeat the method, pick up and replace one of the ingredients to update the crafting result.

Unavailable Recipe Book Method

In 17w14a, clicking on available recipe in crafting book then clicking on unavailable recipe and again on available recipe duplicates items that are required to craft the available recipe.^[42]

Items That are Required to Craft Items that Have 2 or More Recipes/same id Items with the same Recipe

In 17w14a, all items that are required to craft items that have 2 or more recipes to craft them/items that can be crafted into items with same id by same recipe can be duplicated by opening "click for more recipes" menu in recipe book and hovering in it between available recipe and unavailable recipe.^[43] By this method all these items can be duplicated:

• stick
• wool (all types, including bone meal, inc sac, cocoa beans)
• gravel
• sand
• dye
• glass (all types)
• planks (all types)
• flowers (all types)
• iron/gold blocks
• iron/gold nuggets
• beetroot

Chunk Regeneration Loot Dupe

Chunk regeneration allows for duping chest loot found in structures.

Bonus Chest Dupe

From 22w03a (1.18.2 snapshot) to 25w42a (present), it is possible to cause multiple bonus chests to generate in a world. When you first load a world, you can close the game with task manager, then when you reload the world an additional bonus chest will generate. You can repeat this infinitely. This will no longer work once the world autosaves or you pause, since from now on the world will remember that it has already generated a bonus chest. The loot in every additional bonus chest will always be different.

Armor Stand

From 14w32a to 15w32c, destroying an armor stand would occasionally drop more than one.^[44]

Notes

• This article doesn't include infinite villager trading (sticks and emeralds) as it's intended.

See also

• Chunk Savestating
• Block Duplication Methods
• Entity Duplication Methods

References