Other How much play fighting is normal?

I just got two hamsters both males and both at the same time and from the same cage. At night when they are awake they seem to fight alot. One will be on his back and the other on top of him, and they are squealing. I have never seen either bite the other one. Is this normal or do they need to be separated? I have heard that they can hurt each other but also not to interfere if it is only playing. When they are sleeping and not fighting they seem to be good friends, they snuggle together when they sleep and run around freely with each other. That is why I am confused about the squabbling. I would really appreciate any information and advice on what I should do.