Don't worry about it. Your frogs maybe immature, two males or two females. Males will have the following sexual characteristics:
1) call
2) nuptial pads, looks like darkened "gloves" on the fingers
3) 2 small pimple-like glands behind the front legs

Maturity in about 9 months. If you are interested in breeding them, there are several threads on the forum that will explain the process. I understand that they are difficult unless you are prepared. hugging = amplexus.