You could go one further and include the Eguchi bros. Brutal war and KO, but by all accounts they are extremely close, before and after.
Bruce Curry and Monroe Brooks had been friends, but apparently had some falling out before they had their classic fight. I'm surprised Oscar & Bernard haven't had a fallout after all these years of B-Hop being part of GBP. B-Hop had fallouts with seemingly everyone he worked with.