Just let them duke it out. I think clowns only fight to the death when theres one that is about the same size and shape.. and it doesn't sound like you have two that look identical. I would just keep a close eye on them and see how they fair out, but overall, it just sounds like normal clown behavior to me. Also, if they get pretty rowdy, you can just kill the lights. When you shut the lights off, it will calm them down and they will stop fighting. This is how i got my clowns to stop fighting. Now they are best buds.