I don't have any demo or stats dump sorry, actually this bug is not so common, it can happen on jaymod for sure, maybe other mods too

These 'fake' kills appear at the end of the game, not during warmup.
There could be a way to tell those players apart but I'm not sure since I didn't check any stats, and that bug doesn't happen to me, I have just seen it happening to others every now and then.
If I manage to understand how it works I will send you a pm