There have been instances where cycling between a room key and a 'choke event' key causes the latter to become a copy of the former (Ex: I got locked in room C3 by Saiko, find a key for B2 and switch between them, which leads to the C3 key becoming another B2 key).
Likewise, there are other instances where switching between 2 room keys can cause both to disappear but still work on said doors as if you were carrying either key.