Windows is not case sensitive, meaning that mixed cases are considered to be identical. If you mirror (with the /MIR option) it will treat "source\Example.txt" and "destination\example.txt" as "identical" files, and as you said, it will not get copied because there is no need to copy an "identical" file.
I agree with the person that said that this is a defect, however, robocopy employs a heuristic based on timestamp and file size, so robocopy is "supposed to be" defective, or at least, not perfect.
One way to deal with it is to go to the destination and delete the file and then re-run Robocopy.
Another way is to "help" Robocopy detect a change by changing the timestamp or file-size of the file in the source. Changing the file content without altering the file-size and backdating the timestamp is probably not going to represent a change as far as Robobopy is concerned.
Lastly you might want to run cygwin "diff" in order to verify the
work of robocopy. However, this verification itself is not perfect
because cygwin is case-sensitive so instead of doing a comparison of
files "example.txt" and "Example.txt" it will report that one is
missing from the source and the other is missing from the destination.
However, for the vast majority of files where this capitalization
discrepancy is not happening, cygwin "diff" does serve to verify
robocopy.
If you are not familiar with cygwin the only thing you need to know in order to do the diff is that C: drive is written as /cygdrive/c and D: drive is written as /cygdrive/d and just like in Linux and Unix the slash character is the separator. That is unlike Windows where the backslash is the separator.
Suppose for example, an original tree of "Documents" is on C: drive and a backup is on D: drive, the following cygwin command would verify the backup. (Adjust the paths to suit.)
diff --recursive --brief /cygdrive/c/users/userName/Documents /cygdrive/d/windowsbackup/Documents
1
Windows is not case sensitive, so changing the casing should/will not affect Robocopy's ability to copy the file. Are you saying you want Robocopy to recopy it just because you changed the casing in the file name? If so the answer is "no", as Robocopy doesn't look at filename casing to determine if it's changed.
– Ƭᴇcʜιᴇ007 – 2016-08-29T20:48:25.7971Thx for confirming NO. This is a defect IMHO because the casing of a file/folder name IS significant data - and Robocopy allows this to become unsynced while mirroring between source and destination directories. Not sure where one could petition Microsoft to correct/change this RoboCopy behavior... – jtbrown3 – 2016-09-13T08:02:20.873