This bug is a bit annoying for both the victim and the client who has the bug:

Sometimes it happen to see a player which is in your team as an enemy. He shows in the Scoreboard as in the opponent team. But for all other players he appears in your team. When you shot him without killing, you can hear the proper sound that you damage your own mate. But it shows as an enemy in scoreboard and in the player view having the enemy model. The only solution to resolve it is to do \reconnect.

I don't know yet why this happens, i will make more experiments to find exactly how or why it happen.
I don't play a lot on the public right now, but i've seen this bug at least 2 times both as victim and client. Ppl from beer freezer public server saw it more times i think.
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epsislow