Bullied rabbit??

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
Zena are you sure they are both female ?  If yes, it is an issue for dominance - one is , as you put it so well, a bully.  This will not disappear.  They need to be separated or both neutered. OR breed - once breed they will get along fine again until they kindle - then they will fight again.