Thanks everyone for responses... you're right. I would like to keep them together (tank has 200liters) but size makes me worried. That is why asking for comments. First of all. They're separated now (to let every "do what you want" responses to know the status). And here are some more details (I simply opened diary):
- they were together two months (not two weeks - that was misspelled).
- bigger one is now in starving period (as every year is) and will start with eating in March.
- bigger one has never eaten rat. Just mice (4-6). Reason is she is afraid of rats (?!). She simply deny to eat them...
- smaller one was eating 2x a week in the same tank. No issues.
- during shed cycle was smaller one separated (2x)
- they never shared hides (till last week)

so change in behavior made me ask here.

Anyway: now they're separated three days and I see another change...

1. Bigger one is active also during the day (not only after the dark as usual)
2. Smaller one stopped eating (she passed so far regular feeding period day)

?