Hi there and welcome to the forum.
If she is in with your boy, it is likely that she would be pregnant, and the same with her sister.
Did you have them in together because you are wanting them to have babies?
If your girl is pregnant, you will need to have a separate nursery cage prepared, as a new mother shouldn't live with a male. Partly because the male can be aggressive to the babies, partly because the mother wants privacy as delivery day is near, and partly because females can become pregnant within 24 hours of giving birth.
You may also need to replicate that with the second female.
You sound quite new to rats (forgive me if I'm wrong about that) - I would recommend doing lots of research about how to care for rats especially in the event of pregnancy. I would also recommend shifting your boy into a separate cage in case one or both of them aren't pregnant yet.
It is quite a wonder to observe pregnancy and babies and all that, but it is also a lot of work and extra expense so I would say the more information you have the better.
Hope that helps.
Below is a link about setting up a nursery cage. Although normally they don't start to show until week 3 (they are pregnant for 21 - 24 days).

 

Heya! I’ve had a fender mishap with my rats before resulting in pregnancy she does look a big pregnant but if you look for sign eg hair loss on her belly and a bit overprotective then it’s very likely, her and her babies will need a new cage separated from the dad and make sure you don’t touch them until they have fur or (sounds gruesome) the mother could eat them! I suggest putting the 2 cages near eachother so they can still interact too! You may even want to consider neutering your male! But I can promise the baby rats are ADORABLE once they’ve grown fur!!!