Feed them separately and then remove all food. Food aggression is quite normal in dogs.
My GF has an Old English Sheepdog and she is very food aggressive and eats like a pig. She'll eat Tuckers food if he's not guarding it constantly. I have a gate on my kitchen and I feed Tucker in the kitchen, gated, and feed Maggie (the OES dog) on the balcony. After they eat, we recombine them.
There are still a few 'toy issues', but Tucker just gets up high and eats his rawhide where Maggie can't reach him.
Proper management typically can resolve most problems. Her dog is allergic to pretty much everything. The meds makes her dog constatly thirsty and Maggie will drink until the bowl is empty (if allowed to do so) and then puke everywhere. (It's actually kinda funny…) We keep the water gated in the kitchen and only allow her short visits to the water. Either that, or we put her on the balcony with all the water she wants and let her drink and puke to her hearts content. ;)
Yes, it's kinda weird, but what can you do?
