You are going to want to keep an eye on them as the humping is a dominance behavior and it sounds like they are still “deciding” who is going to be the dominant bunny. Unfortunately when they hump “incorrectly” nasty horrible wounds can be inflicted if bunny bites the other rabbits genitals that are right in their face. This can happen to male, female or fixed rabbits.
I would keep a very close eye on them for fighting- they are getting more hormonal now as evidenced by the humping and fighting could soon follow.
How old are they now? It might be something to consider separating them before they have a big blow out fight. If they do get into a serious fight it could end up costing more than 2 neuters just to treat teh wounds AND you have the negative expereince to try to overcome with them. Bunnies are smart and they would recognize another bunny that seriously attacked them- even months later.