I'm no expert but I can tell you what I heard and read - I could be wrong on all counts but it's what I've been reading.
If you're planning on bonding two bunnies, it's best to wait until they're fixed to bond them. They act different (and are usually more calm) once they,re fixed.
Two unfixed bunnies could possibly get a long until they reach adolescence - they they might and probably will fight.
Two unfixed adult rabbits can be bonded but it could be difficult - especially since females are territorial (they might never get along without being fixed either).
If you do manage to bond two unfixed females, and then get them fixed - you might have to get both done at the same time - the vet smell seems to revert the bonded pair to being strangers again and you're back to square one. I brought in my baby to the vet for a nail clipping (20 minutes there at the most) and he smelled like the vet,s office.
I'm waiting to bond my two males - the adult is fixed and I'm waiting for specific anatomic parts to make their appearance before the baby gets fixed. I'll try to bond them then. Right now my young male is very, VERY hormonal and territorial and I couldn't bond them if I wanted.