Does anyone have experience of a dog chewing a sibling or kennel mate's coat?

Friends have a pair of young brothers (Siberians) who lives with a larger group of adult Siberians. At 16 months one of them has started nibbling his brother's coat leaving the double coat clipped very short in a large patch across his shoulders. The nibbler is the more submissive of the pair and nibblee is quite a dominant young man. The dogs are worked in harness and get plenty of exercise, don't appear to be nervous dogs and are on a diet of high quality kibble supplemented with meat.

Is this a case of brotherly love or can anyone think of another explanation and better still, something to deter the behaviour? They have tried putting things - such as anti wound chew spray - on his coat to no avail other than putting the rest of the dogs off going near him but not deterring his brother.

I'd be grateful for any advice I can pass on as they were rather hoping to show the nibblee this year although it's not looking good at the moment!

I've seen it in one Cavalier years ago -he turned all my other dogs bald, and I also have one Malinois (no, two in fact) that will start to rip out and eat their OWN fur. In all instances the solution was the same: give raw meaty bones to chew. I can always tell with the Malis if they haven't had enough bones as it starts then. (I.e. it is down to boredom and wanting to chew.) The Cavalier stopped entirely when given bones.

My middle Flattie did this to the older one when he was about the same age, his lovely mane was reduced to stubble in no time at all, most annoying when he had a few show entries when this started.
He has mostly stopped, 3 year old now, but occasionally he has a bit chew and he is very determined when he does it. It does seem a nervous habit with these two but when he was at his worst I couldn't deter him unless I was either constantly with them or had them seperated.

One of my cavaliers likes to chew her own ear fur and that of her sisters.. always done at night and much more common when she is in season ? I know other cav breeders/exhibitors who have experience of this too. Mine has been known to sick up a fur ball as a result :-(