At about 12 weeks old I had to separate my group of 3 brothers. When those hormones come in they get excessively humpy, and as a result this usually ends up irritating the other buns on the receiving end of it, and fights result. Neutering does damp this down a lot, which in turn helps lessen fighting issues since it then only becomes about dominance and not hormones. Of course there will always be a small amount of dominance humping, but that is usually for short amounts of time and not very often, especially once they have been bonded. It's the excessive hormonal humping that leads to the most problems, as those boys just don't let up once those hormones are raging. Keep in mind that even post neuter it usually takes 3-4 weeks til the hormones have faded enough not to continue to cause problems, so rebonding may need to wait until then.
Now my neutered boys hardly ever hump each other, just once in a while when something riles them up, then it's usually over within a minute and they are back to grooming and snuggling each other.
