I didn't mean a mated pair necessarily. But what would happen is if you got two of close size (males) they would fight somewhat until one became dominant and turned female.
Though I suppose you could get lucky and grab a male and female, most people suggest buying them with one being larger than the other. Buying a mated pair IMO would be a waste of extra money unless you wanted to breed clowns, but that's a whole different beast
When I had a pair I just bought the two together though, no mind to gender or anything.