Why does my male robo hamster chase my other male robo hamst

  They are both about 5 weeks old and i bought them the same day. They stay in the same cage, but EVERY DAY NOW, the same one is chasing the other. I thought maybe the one being chased may have been a girl and they missjudged the sex at the store, but no. He's a boy. He doesnt have nipples. So i want to know why my hamster keeps trying to bite him in the lower area. Theyre both boys so i know theyre not mating. Im sooooo lost, here!! Help!!
this could be one of two things, either they are playing, or they are in the mood to mate therefor they sometimes fight each other. Also if you have two hamsters from two different litters living together, they are much more likely to fight
i had to girl guinea pigs and they would still run around tryin to mate all the time (lol) they're young, they're boys, and they have no rules. give 'em a break; P