Maybe these two greek families made their way up from Michigan, but for the last 50 years or so, the "DeLuxe" Coney Island and the "Original" Coney Island have been battling it out in Duluth. Both are in downtown, Deluxe is on West First Street, and Original is on East Superior Street (the main drag). Deluxe also has a location in "the mall" - which is up over the hill.
Both feature a similar recipe and serving method: grilled dogs, steamed buns, mustard on the bun, dog in the bun, topped with chili sauce (meaty, oily, no beans), and topped with cold chopped onions (ask for your "with" or "without").
Deluxe uses Hormel Natural Casing beef franks, about 10 to a pound.
If you wander into Deluxe, be sure also to check out Sammy's Pizza,(across the street) a northern Minnesota institution - (locations everywhere, seven in Duluth alone) -- cracker thin crust, spicy italian sausage, real wisconin cheese. Superb.