Same sexes will lip lock and flap their tails as well, it's hard to tell the difference between a fight and a breeding ritual, especially if you haven't seen em before. When fighting the same sex they're testing each other to establish who's the boss... and with the opposite sex they're trying to determine if they're good enough to produce viable offspring.
Since GTs are relatively easy to sex by pictures once sexually mature, your best bet is to take pictures of all of them and post em here, that way you'll know for sure... or just wait some time and you'll have an answer.