I went thru a very similar problem when I had the foster boys here.
Having a hidey house with more than one exit is a good idea as well as two of everything else someone stated. You can get one of them really small dish pans and cut a exit in each side.
Yes, it drove me nuts when they did that because there isnt really anything you can do, of course if there is biting and bloodshed then you would seperate of course.
Im not sure if you have any other piggies or not, but do you have a female housed near them? Sometimes if a male thats housed near a female will get aroused and take his frustrations out on his cagemate, mounting ect.
What I did was seperate the grid with a larger piece of coroplast so it's a out of site out of mind idea. Thought I would add that just in case.
Also if you have the room and ability you can try to make the cage a little bigger or give them some extra floor time to get them calmed down a bit.
I made a little mini piggy agility course and my pigs just love it. You can use little pvc tubes for tunnels, and make ramps, little obstacles for them. Of course make sure that its safe and sturdy. This allows them to get good exercise and of course I notice in return that afterwards they are much more calm and chilled out.
I hope that everything works out, although it's normal boy stuff!