Chances are good that even if you do have 2 females in your tank, they were already "prepped for pregnancy". Meaning that most Mollies from your LFS
have stored up sperm, (from being in a tank w/ males), and can even have multiple births throughout their lives.
Props to you for using a breeder tank btw!
As far as caring for your fry... make sure the breeder tank isn't too close to the light or heavy water current. When I had my fry, I fed them finely crushed flakes. I put the flakes in a plastic bag, crushed them, dipped a toothpick in the aquarium water, then in the bag of food, then in the breeder tank. It gives them just the right amount. Although, sometimes they might not eat all of it and it will begin to gather in the breeder tank. If you slowly lift one side of the tank, (keeping the lid on), the majority of the wasted food will slip through the slits.
Oh and just an FYI, I found an extremely small fry come flying out of my HOB
filter when I lifted the media. I was surprised that it was actually alive! And, man was it tiny! So, it's always a good plan to lift your media once a day, (even if you don't think your fry are small enough to fit through the slits on your filter intake tube).
Hope this helps! Have fun w/ your babies!