Silver GSP

A friend of mine has a 10 month old female GSP. We have been watching her for him while he is out of town. She has a 2 year old room mate that is in the same dog run with her. The concern I have is that when it is feeding time we give her 2 cups of dog food and she will eat it up then sit down and through it back up, then eat it again. She does this about three times then it stays down. Then we will feed her the next two cups of food, Same thing. I do know that she was competing for her food at dinner time with the other dog but in the last two weeks we have been separating them at feeding time. She does seam to eat fast but not as fast as my GSP and he has never thrown his food up. He feed Purina Pro plan for puppies.
Any one have any ideas what this could be? Or what we can try.
Even splitting the food up in half has not worked.
Thanks
Jeff