Actually there are a few cases when VERY VERY VERY VERY VERY VERY very very experienced keepers have kept a cham and what was it a geko or some other kind of reptile together and they have had no problems.
But I would not recommened for ANY ONE to do this.
I just thought Id point out that it has been done and done successfully.
For what purpose it was done, I dont know.
But its best to avoid situitations that are potentionally dangerous.