Separate roos?

I have a total of 12 chicks. 6 are straight run columbian rocks, and 3 are "pullets" and three are "red pullets" (TSC didn't give me more info on their breed than that...) Well, the last about 48 hours, two of the columbian rocks who have slightly longer combs (i think? The one on their beak) than the other four have been hopping around in circles flapping their wings at eachother and sometimes trying to peck each other's necks. They are scaring the poo out of the other 10 who hide in the opposite corner when they are at it. Right now their brooder is a 4' X 2' X 2' cardboard box with chicken wire over the top. It still isn't warm enough to move them outside, and their coop is on the edge of the woods about 100 yards or so from the house, so I would be worried about predators.

They don't seem to be really hurting each other yet, just scaring the others mostly. But I don't want to wait until someone gets hurt to do something. If they have a bigger area will the little fights stop, or is it because it is such a small flock? Or maybe they will just never get along. They Columbian Rocks are about 6 weeks old, while the pullets are about 3 and a half weeks.