I have never personally dealt with this, but I have seen it.
My son used to take horse riding lessons and there were all kinds of boxers there! They also had a pair of black labs that were brothers, but from different litters. Well the younger one used to constantly lick the older one. So much so that he was rubbing hair off! They had some sort of spray from the vet that they sprayed on the older to keep the younger from licking so much. It was weird!
Two of ours did that. Calli would actually groom herself like a cat (she was raised by two cats so that could have something to do with it, the cat groomed her when she was a puppy). Ziggi is always licking himself......very annoying and we are always yelling at him to stop. The other two never had a problem with it.