Extra masks and mask sets copied by history stack copy
Copying a single module results in masks from all modules being copied.
I created 3 instances of the exposure module. In the first I set exposure to +1 and with drawn mask, I drew a 1. Repeated for the next two modules at +2 drawing a 2 and +3 drawing a 3. I then moved to light room and copied the instance of exposure compensation that I had used to draw the 3 on to a fresh image using history stack copy (selecting only the one module) and paste all. In the copied to image you can see "grp exposure", "grp exposure 1" and "grp exposure 2" with all their brushes. I would expect just the group and brush(s) from the copied module to show up in the mask manager of the new image.