Honestly she sounds like a whore, if anything hit it and quit it, and that's real advice. It's not like your friend and her were ever even dating, they just got drunk together and she wasn't interested so what does he have to be mad over? It would be different if she was your friends ex or if she was actually into him, but that's not the case.
You ever hang out sober with her?
Seems to me like you just met her and don't you find the whole 'perfect because I'm the male version of her" a bit strange and narcissistic. Based on how you described everything it seems like you weren't even that interested until after drinking a whole bunch as well. I think you should try and re-think it over and stay friends with your bro cause they came way before this person.
If you keep hooking up with the girl you will be constantly reminding your friend that she chose you over him which will make him feel inferior/jealous. He is going to hold some resentment for that.
Interesting read - I think you should plan a 1 on 1 date/hang out event and see her intentions then. Get to know her more better, and if she is compatible than I guess go for it? BUT, make sure she isn't doing this kind of stuff on the daily with other dudes. Truth hurts, but overtime your friend will be accepting with both of you together (externally that is). As kmjt said, mentally he would probably be mildly upset. Strange that she would say she is the female version of you, not sure if drinking was involved here - but as Boney pointed out, slight narcissistic much?
Let us know how it goes.

