That is how they play by jumping and biting each other and it is normal and seems ruff sometimes. You can usually tell when one doesn't want to play and the other keeps messing with him. That is when I would seperate them to give the other one a break. I have to make Kodak stop playing when Kamari is walking away or lays down and he keeps pulling at her. Just moniter how they play and if one gets rough then break it up. I've heard Kamari whimper and I make them stop and seperate them for a minute. I seperate the more forceful one behind a gate to show them you can't play so rough. Give them lots of squesk and chew toys to keep their attention towards playing and not fighting so much.
