KFC's Double Down sandwich is just an Atkins grilled cheese.
You can also order it with grilled chicken filets, which somehow sounds grosser.
An open-face Double Down is basically a diner entrée. Remove the bacon, change the sauce, and it's Chicken Parmesan.
Idea: Hawaiian BBQ Chicken Katsu Double Down steamed rice and macaroni salad sandwiched between two fried chicken filets.
Idea: McDonald's Double Mac two fried chicken patties, special sauce, lettuce, cheese, pickles, onions with a sesame seed bun in the center.