Is this behavior normal in hamsters?

two weeks ago, i bought two male roborovski dwarfs from the pet store. they've been getting along fine up until two days ago. on occasion, one hamster will chase the other around the cage, and the one that's being chased will burrow under the bedding. the same one that's doing the chasing will also kind of push the other one, or flip it over onto its back. there is usually some squealing from the one being flipped over. i've looked both over, and so far haven't seen any scratches or cuts, and there's no blood on the beding. is this behavior normal?