Are they fighting or playing? Bulldogs usually play pretty rough with each other and it could appear as fighting. If they start getting too rough, you can separate them and give them a time out.
My Frenchie played VERY rough with my other, larger dog. If you weren't in the room and just overheard them, you would automatically think they were fighting, but it was just really noisy, rough play. Posting a video would help assess the situation. As long as one submits and backs down, you won't have issues.