weird behavior

Question
I have two red ear sliders that are a little bit older than a year i say and are in a 40 gallon tank. They continue to go up to one another and place their front two feet next to their heads and wave their toes at one another at a very fast pace. Im not completely sure if they Are male of female either. What does thius mean?

Answer
I am not sure of their size but in RES this is like a mating ritual. Like a dance.
They will go to eachother and wave front feet, head bobs, then a male will grab the female with his long nails and begin to mate from behind her.
Long nails are a sign of male, shape of tail etc.