Honestly I think that if you allow people to make more than one character, with the number we have already it'll get chaotic. Too many characters can kill an RP just as quickly as too few. Maybe if not everybody ends up sticking with the RP and we seem short on characters then people could play multiple. But for now I think it's too much.

And about you playing two characters but not everyone else. You're the GM, you kinda get to do whatever you want. Personally, I don't mind at all.