I agree that its natural behavioir. They can get aggressive if another dog trys to get their toy. And of course, the toy that the fist dog has is always the one the second dog wants.
I let them work it out and only intervene if the fighting looks too rough. They should know the signals denoting when one is getting too agressive for the other. This is rare. I dont buy into the pecking order you mention. What I have seen (and others have discussed here) is that there is no usual pecking order. The dominance heirarchy changes constantly. I have seen it myself with my guys... Just when it seems one is the Numero Uno Top Doggy, they switch and that yorkie will make submissive gestures to the other. Strange but true.
