Veiled Chameleons, along with most other Chameleon species need to be housed alone. Having two males in the same cage would result in non stop Territorial threats. And if you try and put opposite sex's together, they are probably going to try and mate, and if not, ones bound to get hurt.
But if you had a tall enough cage (like 5 to 6 feet for fully matured chameleons) you could try it just watch closely how the interact!