As much as some species of hamsters can be ok together, I would always advise to keep them separately. Since they are squabbling and one of them seems to be dominant, I definitely think it would benefit them. Hamsters do best kept on their own, even if some of them are okay with living in a pair. So, the short answer is yes. I hope you can manage this and get a second cage!
if it's financially difficult, maybe you could make a bin cage?