If I have 2 characters adjacent with poison would that cause Bizarro to remove 2 tokens? I assume yes because the damage is coming from 2 different sources, but I just want to make sure.

Depends on what part of his dial he is at. Each character deals poison one at a time.

Remember that Poison is a Free Action. So each use has to be resolved separately before using another.

And what happen with bizarro and mistress death ability? He came back with all his tokens?