I have a 7yr old pit bull and a 1yr old pit bull. Both females. Get along fine with each other, obey commands such as sit and stay with ease, and eat from the same dish or chew on the same bone at the same time. They even wait their turn for treats. Both will immediately drop what they have when "drop it" command is used. All bets are off when a squeaky stuffed toys are out. The 1yr is only interested in the toy the 7yr has. Doesn't matter if I give her 3, only wants the other. Had one outside and one inside as well as in separate rooms. The younger one will whine at the door and barely even touch hers. Eventually the older dog gets bored with hers and wanders off. 1yr will then beeline for the discarded toy while 7yr goes to inspect what the other got. The problem is when the 1yr is like "hey that's mine" and goes after the toy she originally had that she is suddenly interested in now. I have separated a major fight a few times because of this behavior. Pretty sure the problem started while the 2 were mole hunting outside at my previous home. They only way to have the 1yr chew her toy is when she doesn't know the 7yr has one too. But she is starting to catch on that when she has one so does her sister.