what have you been seeing your torts do to each other? are you sure they are female? keeping russians in pairs is very dangerous, this could result in a bad injury to one or both of the torts.
1 tortoise mounting another is not always for breeding. It could be a display of dominance and aggression, too.
Are you sure you have 2 females?
Are your 2 housed together in a pair?
Do they live indoors in a tortoise table or outside in a nice sized yard?
Many people have difficulty keeping tortoises in pairs, especially when housed indoors. You could try keeping your 2 separate or in a very large outdoor yard so they can get away from each other. If you are dealing with female mounting, then it's a sign to make some changes.
No they do not try to breed other females. They do sometimes mount other females in an attempt to show dominance and drive the other female from their territory.
If you are seeing this, you have a problem. Your tortoises need to be separated.
The tortoises in your pics also look pretty young. It is difficult to sex them when they are that size. Are you sure you have two females?
Even without physical injuries, the bullying causes stress and that alone is enough for one tortoise to get ill....even die.
Russians are anti-social tortoises.
I had one that I was baby sitting round up and chase two great big Redfoot tortoises around like a sheep dog. Snapping at them as they ran in circles.