Windows keeps automatically adding EN-US keyboard layout

Question

Windows 10 keeps automatically adding EN-US keyboard.
However, Windows is being installed with the correct keyboard layout but somehow automatically adds EN-US.

I know that it can be fixed by going to the control panel, as shown in this thread: keyboard layout (United Kingdom) is automatically added.
However this does not tackle the root issue, which is: Why does Windows add the keyboard in the first place?

A solution for this is extremely handy in WDS/MDT/SCCM environments, where new PCs are being deployed all the time.

Answer 1

This issue has been found in the base image of MDT. In settings -> Time & Language -> Region & Language -> Additional date, time & regional settings -> Region -> Administrative -> Copy Settings -> Under Welcome screen was the wrong keyboard.

This can be fixed by marking "Welcome screen and system accounts" and pressing OK. Of course this has to fixed in the base image as well.