Barbara, my Zoe does the same thing! Except Azriel doesn't get mad that she can't take Eddie's second spot, she just looks really happy that she got the first one.

I hate it when Eddie is all curled up and happy and Zoe takes her spot. She'll start by licking Eddie's head, and if that doesn't work she'll start on the ears, and then Eddie leaves and Zoe moves in. I've even seen her do it to Eddie when Eddie is sleeping in the middle of the floor (don't know why she does that). Now why would Zoe decide she has to sleep in that particular spot on the cold floor? Because Eddie is there. Meanie.