I don't think a pair will make a difference IMO, just like clowns *needing* to host something. Just do like VooDoo said and get one that is either bigger or smaller
I've definitely seen orange and black pairs before though. Not sure on how they were introduced though.
As for the biting that's territorial, clowns are damsels so they can get a tad aggressive. Biting = get out of my tank!