I tend to take the stand that dogs are dogs, and the different breeds are more alike than different. There are exceptions to that, and the eating habits of the typical Lab and typical Shepherd, are completely different. The Lab will eat what ever you give it and look for more, gleefully eating their way to a life shortened by obesity. On the other hand, a Shepherd will keep itself lean to the point of bonyiness. Posts like yours are common.
I would cut back to one chow, the Nutro large breed if you like it. Once a day, separate the dogs, and put down 3-4 cups for each dog. After 15 minutes, take up what isn't eaten. Limit what else the dogs eat, no more than a token taste of your food, and not too many biscuits. They may not be too bad, since many of them are formulated much like dry chow. If you are using them for training, use small ones or just break off little pieces.
You need to keep both dogs lean. The Shepherd may never eat as much as you think it should, dogs seldom harm themselves by not eating enough. It can be tough. I had a Shepherd go 3 days without eating. I was a wreck, but she was fine. The chart below will help you keep both dogs in good shape.