Most all my gun cases are singles. I tried a double case similar to what you are looking at for an AR / M1a combo. By the time I added the guns, magazines, and assorted odds and ends, the case was really to heavy and bulky for practical use, except for carrying from the truck to the range.
I much prefer the option of well designed a fleece back pack to carry my gear, along with my primary weapon carried on a sling. Usually when I carry a second weapon, its a handgun, but if it was to be a second long gun, it to would be on a sling, across my back, or taken down, and stored in the pack.
Larry