Ditto that. If they fought once, I wouldnt leave them in together again. They clearly don't get along with others while nursing.

I have a few female rats that are very territorial, and pick on the "newbies" so to speak. Although the newbies have been around almost as long, the other girls were there first and always let the "newbies" know it. They will bully, nip, scrap and all around get pissy and loud.

Would I ever put those two rats together in the same tub to nurse? Heck no, I'd lose both litters.

I always advocate leaving mothers to nurse by themselves. It's how they prefer it in the wild, they prefer it in captivity.