I've just had two comments on Subtract boolean from float in python deleted. One was the standard possible duplicate comment, which gets deleted when the post gets marked as a duplicate.
The other was another comment indicating a potential alternate duplicate; this one. It was something along the lines of:
A better duplicate might be Is it guaranteed that False “is 0” and True “is 1”? but it was closed as a duplicate of the first question
I've done some science. It appears as though the word "duplicate" is not enough; I wrote "duplicate test comment" on java.concurrent.ReentrantLock - why we want to acquire the same lock multiple times but it didn't get deleted (I did it manually).
However, on java.concurrent.ReentrantLock - why we want to acquire the same lock multiple times I wrote "possible duplicate test comment [test](some question)", this comment was deleted.
At a guess, all comments that have the word duplicate in them and a link to another question are deleted once the question is closed as a duplicate. This might be solely comments that are owned by someone who voted but I'm unable to test.
This shouldn't happen. Comments pointing out separate linkages can be incredibly useful and make the web1 a better place.
1. Pun intended; please tell me someone noticed ;-)?