Nlmadison, I think you have a situation on your hands. There is no larger species/variety of ADF. There is only the African Clawed Frog, which is very different than ADFs. They are voracious eaters and get much larger than ADFs. When adult, they will eat ADFs and attack/eat even large fish. They also need a much larger tank. Perhaps this is your answer.
As for the rock, if you think it somehow may be the culprit, you need to work on securing it somehow.
Please look into this matter. The quickest way is to look at the front feet of the larger "ADF". Are the toes webbed???
If it is an ACF, not an ADF, you will need to find it another tank ASAP.