problems with alpha male

Question
My two male rats are around 20 months old.  I'm worried because the alpha male, Mallie, does not let the submissive one, Quentin, eat properly.  I've taken Quentin to the vet twice before for fighting related injuries.  The vet said fighting is normal and the injuries weren't serious enough to warrant separation.  They get along fine most of the time, but when I feed them Mallie hoards the food in a corner and will still fight to take away whatever Quentin is eating.  Quentin only gets very limited access, especially now that he's older and not as motivated to fight for his food.  Mallie weighs 17 ounces and Quentin weighs 11 ounces, but again, the vet told me not to worry about Quentin's weight because even though he's smaller, his weight is steady.

I still worry about him though, because recently he got something stuck on his fur and when I gave him a bath I noticed how bony he looked.  I've thought about buying another cage so I could feed them separately.  Is this necessary?  Is there anything I can do to get Mallie to share?  

Also, I've been thinking about adding another rat to the family, but I'm worried that Quentin won't be able to defend the little food he does get against TWO hungry rats.  Is there any way my two current rats and a possible new rat can eat in harmony?

Answer
I know what you mean. There is always gonna be a rat who has to be the boss of everything. It sounds like your vet is right, as long as there are no serious injuries and his weight is steady, he should be fine. However, I do agree that it might be worth a try to feed them separately. Its also normal for rats to get a little bonier as they age.