Are my hamsters fighting?

I have recently bought 2 Russian dwarf hamsters (both male)... They seem to squeak at each other and jump on top of each other. I saw them on top of each other and it looked like one of them was biting the others private area??? are they playing or fighting? Also, one of them always looks sad and when i hold him upto my ear, he makes little noises as if hes talking to me? is this normal? thanks.