Did they continue to fight like this into adulthood? This type of behavior is generally grounds for culling in breeder stock.I let mine settle it. Yes, there are some scrapes and scratches, but they get it over in a few hours unless you toss in new chicks or try to separate them.
Here is one long session of one battle with two brothers that took place one afternoon, complete with dramatic music. You think they're worn out, then they start up again. None of my other chicks have ever been this way except the Brahmas at 5-6 weeks old.