If you have a sheet open while you drag a second monster from the compendium, it can occasionally re-write the info on the open sheet. The system should tell you it is going to overwrite (like it does with a compendium equipment or spell drop), but it doesn't. This is a known bug. Some anecdotal evidence suggests that it only occurs if you drag the new compendium creature to a point on the VTT that is vertically lower than the top of the open character sheet (i.e., this is a "live area"), but I don't know if this has been verified. I would suggest two possible courses of action: 1. Make sure you drag new compendium creatures to the top of the map, higher than the top of any open character sheet. (might work, still dangerous) 2. Close all character sheets before dragging a new compendium creature to the map (Safest) Note that although the lack of a warning is a bug, there are uses for the overwrite behavior. Some people will set up a template creature, with actions and settings they prefer, and open a copy, then drag a new compendium creature to it to create a new creature with their custom settings. I do not recommend this, but it is a common practice thanks to a very old tips video.