Besides the above, if you are fairly certain that he is not the same person, I would probably email him and ask him outright if that were him. Tell him that you felt that it was not despite the fact that you in person were attractive, muscular, and that you enjoyed himself. Maybe he will come clean. If he does not I don't think I would see him again as you probably could not trust him. If he does then you would have to make a decision about whether you would see him and be really careful because he has confessed.