Hmm, this immediately brings to mind the Jet Li movie "The One", which WAS NOT just timecop crossed with the matrix, so shut up about that.
Would I kill my alternate self for superhuman powers? Hmm... well thinking pragmatically if I'm even considering it then some other version of me that's a little more evil is probably already started, so I've gotta catch up! Or what if someone else does it? Wouldn't it be grossly irresponsible of me not to attempt to acquire said super powers first, before a less ethical individual does it? I think we can all see it's best I never have this option...
Would I kill an alternate version of myself to steal his normal, non superpowered life? Probably not, then I have to pretend to be him and that's not gonna last, besides, my current life is fine with no murder involved.