[souffle]

They are at an age when they are becoming mature as well and living in a single sex pair is not natural for them. In the wild they would be in family groups or pairs and sometimes only pairs until the female is pregnant. It's not nice to come down to a serious fight one morning. Even if they are not injuring each other yet the stress of being bullied and chased away from food and areas of the cage can affect the health of a hamster. I wouldn't risk it. They usually 'sulk' a bit for up to 10 days then become much more human friendly and should settle down well.