Females can be just as aggressive towards eachother as they can be to males and males with other males.

It sounds like they are having a typical dispute over territory and one has claimed the bulk of the cage size. They may also just not like eachother but both may get along fine with other females. Also if the younger female is distinctively smaller, probably not a good idea to leave them together.

The size of the cage and how much 'cover' you have set inside can also be factors. Its best to have as much visual barriers as possible. IF they can't see each other then they tend to be less territorial. I also suggest two separate feeding containers one at each end of the cage.

When I housed two females and a male together for breeding I had two-three feed dishes spread over the cage to prevent fights over food. I also had plenty of fake plants to provide visual barriers and to my knowledge none ever fought. (I never noticed any bite marks or other injuries nor indications of weight loss etc in the females or even tail loss. In fact only ever lost one tail and that happened because I accidentally caught her tail in the lid of the cage.) Oh and one baby did drop her tail and I am sure that was due to having three of them in a small cage, so I only ever kept clutch mates in the small containers I used for babies till old enough to be housed in the big cages and/or go to a new home.
-----
PHLdyPayne