You need to learn patience, first of all. It's Christmas, and many members aren't going to be around the forum today.
Secondly.. mounting is common in the animal kingdom as a sign of dominance. Females mount females, males mount males. It's normal.
Thirdly.. YOU need to check genders. You need to check the gender of the one that will let you touch her, if that one's a she for sure, you probably don't have anything to worry about. What are you feeding them? It's common for older animals to gain weight.. which is why you need to be careful with how much you feed them.