Bullied rabits?

Question
I have two female three month old dwarf lops who are sisters, I've had them for about two months and up until recently they got on fine.
Yesterday evening, I checked on my rabbits and stroked them for a bit, and noticed one of the rabbits was clambering all over the other, at first I thought this was fine, but became concerned when she started to pull out hair that was not loose on my other bunny. I separated them by picking the 'bullied' one up, but as soon as I put her back into the hutch the 'bully' chased her and jumped on her and continued pulling out her hair. The bully also tried mounting my other bunny...but they're both female??
They are totally opposite in characteristics, in that one is really outgoing and the other is very shy towards me.
I have separated them temporarily (the 'bullied' rabbit is currently living in a run indoors- ideally I'd like them to get on again).
I have also noticed that they seemed to have swapped personalities since being separated; The 'bully' is now very timid and shy towards any contact, and the other rabbit is now outgoing. Any advice would be greatly appreciated.  

Answer
3 months is usually the start of when females get hormonal and territorial. The mounting and aggressive behaviour is very common of hormonal females. The mounting is for showing dominance. Getting them spayed when they are old enough (5 to 6 months, though some vets will spay as early as 4 months) will help out a lot. Don't wait too long past 6 months, though, as the longer you wait, the more likely the behaviour is to set in for good.

For now, I would suggest keeping them in seperate hutches/cages, but still let them play together in a neutral area (like an enclosed play area on the lawn) while you are watching them. This will make it so they continue to remember each other and stay friends. That way, once they are both healed from being spayed, they can live in the same hutch again.