To answer your earlier question: 2 small one's should ultimately end up being a pair. When you get them, especially if your tank is small, you might want to think about putting something on the top to prevent jumping. They can get pretty wild while they are battling to figure out who will get to be the lady. I had a couple of jumpers back in the day. That was sad.
Once they figure it out, things should settle down. Although even from there it can take months before they officially decide to move in together. But it should happen eventually.