Hello, sorry this is my first post so sorry if I have messed up! 
So basically I have two female rabbits named Eevee and Luna, they are sisters and not neutered. Recently Eevee has started humping Luna, she doesn’t try much when they are in their cage but when I put them in their run to play she tries constantly. After a while she will stop and won’t try again until I put them back in their cage. So is it because she gets excited or? I just find it weird that she gets very well..humpy when I put them out to play then calms down.
I did google it and I read that as long as she isn’t hurting her then its fine but Eevee is starting to pull out chunks of Luna’s fur… After today she now has a small bald patch on the back of her neck, I checked the area and her skin looks fine and when I touched it she didn’t show that it hurt, she let me stroke her there as if nothing had happened.
I know Luna is hating it because when Eevee starts trying to hump Luna she will stomp her back legs and makes really tiny speaks. I’m not sure what to do. I started putting a pet carrier in the run with them so Luna has a place to run into but Eevee has now started to follow her and chase her out and they will be going in circles till Eevee gives up. My friend suggested giving her a ball to hump, I tried and she wasn’t interested, I was also told so separate them at play time which I haven’t done yet as I need to get a second run.
Eevee also rubs her chin over everything new I show her (toys, treats) and I read that is a sign of dominance? Also they are weeing all over the walls in their cage, well only in one room of the cage, I read that you should get them neutered if they do that? and I’m not sure if its Luna or Eevee doing that.
Other than all that Eevee isn’t showing any signs of aggression, well she scratches me when I pick her up but that’s expected haha but she never bites or anything. I always see them grooming each other, sleeping next to each other and eating together.
So I’m just not sure what to do, should I get them neutered or will the humping stop by itself?

Also, sorry if this has been asked before, I did try looking for any posts with the same situation but I couldn’t really find anything! Thanks!