Yours is always better!!

Well, they want eat the other's food. I had to put Mimi's bowl inside her cage and lock the door to prevent Cartman quickly eat it all up. In the morning Cartman clearly remembers where Mimi's food was, and jumped into Mimi's cage looking for it, a higher priority than going outside to have a morning walk...
Mimi eats Cartman's food too. And she loves his treat, especially the rawhide ring. She growls when Cartman wants it back. He was not interested in it of course until Mimi wants it. Giving one to each did not solve the conflict totally. A lot of chasing and growling.

Well, back to feeding problem. It seems the solution is very simple: I put Mimi's food in Cartman's bowl, and his in hers. Then, these two silly dogs are very happy to eat their own food from the other's bowl. Peace and quiet, not to mention two full bellies.