It didn't happen in my tank. I bought these 2 fish at a lfs on a friday but wasnt picking them up till sunday. They moved the fish so they wouldnt get sold. On sat someone traded in a fish that got put in the tank with my fish and they got the snot beat out of them The lip might have not been that bad but it was already F'ed up. So no new lip huh...well...looks like I will be trading this one once its fins are healed up.
Keep the water clean either way. I have seen regeneration of skin on fish a few times but have never had a fish as badly injured as that. If it does heal over it will likely take longer than fins do and the area will be scarred.