No, it's not normal. Are you sure these sisters get along? If my sister did that, I'd be furious, or if I did it to her, I'd expect her to never talk to me again. It's SO NOT COOL to flirt with or tempt your sister's boyfriend. I don't see how this would be a good idea in ANY situation.
Still, what are you doing "running into her room and jumping on her bed" if you know she wants to tease you? I'd try to avoid her if I were you.
Perhaps you should make up your mind which sister you're interested in and then not stare at the other girl's ass.
If the situation keeps going the way it is now, my guess is you're going to end up without a girlfriend somehow, and these sisters will be fighting.