Are you certain your frog is a male? Have you ever heard him call? If not I suggest not getting another. Even if he is male, you might not want a second frog calling.
I have two males and while they're fairly quiet and don't call at everything they can egg each other on. It's like a contest to see who can call the loudest. Thankfully it never lasts very long. It only happens occasionally, about once at 2 or 3 am. Frequency of calling probably varies with the frog's temperament.