fancy mice that hop?

Question
i have recently bought 2 female fancy mice. one of them is acting a little strange. she has become somewhat agressive towards her sister almost like she is trying to establish dominance. for example if they both want to use the same wheel we will find her on top of her sister. also she has started hopping at random, it usually lasts for about a few minutes then she stops. i am a little concerned i was not sure if this was normal, id appreciate any advice that you can pass my way.

Answer
Like baby rats, baby mice play wrestle, chase and have a great time.
Also, when they hop, this is normal too.  I have 3 baby male rats right now that are 5 weeks old and I swear, they dont walk. They float, fly, hop, jump, leap, you  name it, but walking is not part of their locomotion.  LOL   They pile up and wrestle in a ball, sometimes all three of them, taking turns seeing who can pin who down first.  I have observed this type of play for many years and they are simply having fun. Its not really dominance, but they will hold each other down until the one on the bottom stops protesting as if he is waving the white flag, but soon as the one that was pinned down is released, its his or her turn to do the pinning. This goes on until they are tired.  You will also see them hop all over the place, climb the cage, swing from the bars....they fly at this age.  Enjoy it.  They are fun to watch.

And as for the wheel, buy a second one.  This way they wont fight over it.