If they're still small, then theoretically two of the same size would get along because neither are in competition for dominance as yet. Eventually they'd pair off, deciding who gets to be female by whomever wins the most arguments (
I know it sounds like I'm making innuendo, but I'm not.
).
If you're not 100% sure if you have one that has started the transition from male to female, the best best is to get a smaller one as the newer. IMHO anyhow.
