That doesn't change the fighting.
They will either need to work it out or one of them has to go. They always get along until they don't. Your separating them might be prolonging the fight.
Think of it this way... I never lived long term with my siblings without having some disagreements.
This time of year.. hormones are raging.. and they've got LOTS of energy to expend. If there is a low enough boy on the pecking order... he becomes the mate and may be mounted over and over... or they may even mount each other. Keeping a stag pen is NOT all peaches and cream the way some would lead us to believe!
Add in more visual barriers if possible. More feeders and more enrichment.. like digging in a compost pile or hanging corn on the cob or cabbage for them to jump at.
Also, for what it's worth.. stag pens are actually a bit more peaceful with MORE boys, in MY experience... it spreads the pecking order out. So when one starts something another comes around and it looks a lot like a pool ball table reaction...
If things don't settle down, you might consider splitting your stag pen in half so each get their own space. Even though they are alone they will be in sight and sound of each other.
But, do keep in mind that it can look like a whole lot of blood when it *may* not be as bad as it appears.
For me.. If I get one relentless boy going after another.. I put the chase and beat down to the one doing the chasing and beating down. My version is using a long pvc pipe and tapping it behind them.. until their
focus is redirected at least for the moment. Hear the saying that the best defense is a good offense?? It's true... you go on the offensive until they are now having a healthy (not excessive) fear for their own safety. Sometimes I DO wallop them if needed, being sure that I'm in control and NOT just swinging wildly with frustration. It doesn't need to hurt them it just needs to startle them to snap their brain into a different place. That whole carrying thing MIGHT help attacks directed at you but it will likely do nothing for their personal disagreements.
Honestly.. it's always trial and error to see what works since all birds are individuals. If all else fails.. depending what breeds you're working with.. you might be able to use something like Pinless Peepers.
The MORE human intervention...
if they are staying together... the longer it will be drawn out. Humans are not part of the pecking order equation and them boys have very one track minds.
Hope this helps some!