Multiple Man is not one of the mutants I am most familiar with. I saw him in the third X-Men movie, where he was played by Eric Dane from Feast and Marley & Me, and I've seen some of his comic book appearances. If you were to ask me, though, what he's like – maybe what sort of music he listens to, who he'd likely look up to, if he's a Betty guy or a Veronica guy – then I'd not really have much of an idea.
Next Summer, though, it looks like we'll have a chance to get better acquainted. According to Comic Book Movie, there's a role for the young duplicator in the X-Men: First Class movie that Jane Goldman, Matthew Vaughn and co. are cooking up. The site reports that "at least three young actors have been seriously approached to fill the role", which you can wilfully misread if you want, this being Multiple Man and all.
Something's telling me that there's going to be a simply epic Comic-Con unveiling for this movie's ensemble cast.