I have that quite a bit with my boys. The one that irks me the most is when Mason takes a toy away from Angus and then ditches it. He doesn't want it, but he's just stirring.

I've found being sent to the bedrooms to be the best for us.

Sometimes I don't know what to do but I have noticed that the younger one stirs the older one up a bit too so it's not always one sided.