Becca, you might want to reconsider keeping up high value items (ask your trainer or someone here...)...I think it's probably important for them to learn to respect each other's space and "belongings" while they're still young and able to work it out calmly. I don't think this is a sign the dogs will turn D/A but if in six months one of them snags a bone or something or you forget to pick it up or whatever, and the other tries to grab it, that might not turn out so pretty.
"My favorite color is green, green like newly cut grass. When it comes to green with envy, though, you can stick it up your @ss!" ~ Grammy