It's been a common problem for UOSteam on OSI servers for years now. It happens when you cross serverlines or dungeons. Life bar names will change to some random pet in your stable or a random party member or random person you've last seen. And health bar itself often doesn't update. It's actually an Enhanced Client bug that is for some reason persistent with UOSteam, probs because of whatever packets they're using to handle mobiles.
Solution: Use Razor Enhanced.
