If you are to reintroduce them they must be neutered first. Otherwise they will fight and they could actually kill each other. They would in any case hurt each other very badly.
A female bun would make them super-competitive and even more belligerent. They probably would hurt the female as well and if she survives you’ll have lots and lots of bunny babies, so it’s not an alternative.
If you get your boys neutered, you might be able to reintroduce them after 1-2 months, but there’s no guarantee they’ll ever get along. They fought due to hormones, and it’s what two intact males will do. But if two buns have become real enemies, stopping testosterone by neutering is rarely a cure, , the buns will still be aggressive toward each other.
In nature rabbits have vast areas to run over, so fights end when one male decides to remove himself from the scene. In a cage or another limited space, there’s nowhere to run and hide.