My buns have been bonded for about 3 months now.  Arduina is definitely the more dominant bun.  They have been doing good living together and I haven't needed to separate them since bonding.  

I think Arduina is a bit jealous when we pet Leo though, because she either comes over to us and starts trying to climb up on us or nip at us, or she'll try to mount Leo.  She asks for grooms he grooms her, he as for grooms and she ignores him.  Leo is very submissive to a very bossy ladybun.   The only time we see Leo with some confidence is in the morning before pellet time, he will chase her around.  We have to make sure that he gets some food, because Arduina eats 2x as fas as Leo.   Arduina just seems very mean to Leo.  She is constantly getting yelled at for either nipping at us or doing some other sort of 'bad' behavior.  She's a little attention hog.  

Is this normal to have such a difference in dominance?  

three months isn't that long. they will keep evolving. doon't worry. females are complicated to begin with. She may see Leo as hers now too so there could be jealousy both ways. I would make a point of giving in a little to her demands and over time she should mellow out.