Just curious... how do you feed them? Do you just let crickets in and the Frogs hunt? There is a possibility that only one is getting the food or most of it so it is growing faster if this is the case.
Yes usually the females are larger
Did you get them together? Australian Whites are larger than Indonesian whites? Just some size difference possibilities.
I have greys and I have a unusually large male that is as big as my big female (I think its a female lol). So the size determining the sex isn't always accurate 100% apparently in some breeds of frogs.