Hi, they look very young, how old are they now? You can keep them together until 10-12 weeks or a bit later depending on their temperament, you will see signs when they start humping each other and chasing/circling you will have to separate them before they start fighting, because even after neutering (you will have to wait about 2 months after they neutered to start rebonding them) if they had a major fight they can remember that and if will be very hard if not impossible to rebond them.
Generally it wasn't great idea to get two brothers tbh. I have adopted two pairs of brothers from the same situation, one boy has horrible scars and a hole in his ear, he also had bad scar around his eye but thankfully it healed already he's just lucky the eye itself wasn't damaged.
Other pair also have some scars on their backs and on ears but healed nicely you only can feel them with your fingers but they are not visible as fur grew back. When they start fighting it goes very quickly and even if you are there you won't be able to stop most likely.
The second pair both boys were neutered immediately after their first fight and stayed separately for 6 weeks, then they were put back together and they had a fight again so people just gave up on them they were too scared and kids were horrified.
So please separate them at 10-12 weeks before they start fighting and keep separately until 2 months after neutering, then do research on bonding rabbits and follow instructions you might be able to rebond them.