Here'a another one of my weird questions...

So there's two universes, two of many in a many worlds/multiverse scenario. We'll call one Universe A and the other Universe B for sanity's sake. And there are two people, the exact same guy, but one from each universe, so Guy A and Guy B.

Hand wave how Guy A would "travel" into Universe B for now. Since two of the same thing can't occupy the same place and time because they would annihilate each other (Guy A and Guy B would blow up upon contact (that's a sci-fi assumption so forgive me if that's way off). Would it make a difference if Guy B in Universe B was already dead before Guy A appeared in Universe B?

If Guy B is already dead wouldn't everything about him be so completely different from Guy A that Guy A could then inhabit his space in Universe B?