If a guy ID's himself to you as a PUA then help him or get the hell out of the set since you don't know what's going on. It does happen by accident that a wing takes the target, but that's bad communication from the wing to the PUA.
When I go out and wing I know what my buddy's codes are for who's the target, when the want to eject, and whether or not I can try to recover the set. The reason I know this is we plan in advance.
My advice to you if you come upon someone elses set and you don't know the guy, bow out gracefully, and find another set. Work together not against each other. There are billions of women on the planet, go find another.

A good wing can tell DHV stories about the other guy, and build him up. He has stories and routines prepared to help the PUA achieve isolation. He brings a good energy to the set, and the PUA has to DHV intro him. If you can't do this, get the hell out of the way.