Brother and sister rabbits fighting?

First as they are brother and sister you shouldn't allow them to breed. That is irresponsible you should never breed close relatives i.e brother and sister rabbits it could cause gentic problems with any off spring. It sounds like the male wants to try and mate her again and she doesn't want any of it . Rabbis do chase around but it can sooner turn to fighting. Rabbits usually grunt when they are angry or not happy .Please be responsible and keep them apart till you have had them neutered .