I have several duplicate kits, like the '60 Starliner. It's a great kit built straight out of the box or as a chassis/drivetrain donor for like the '61 or '63 Galaxie. I always have lots of Mustang kits and just about every pickup.
When people buy me a kit for Christmas or something, they tell me they had a hard time picking a kit out. They want to get me a kit I don't have. I tell them if it's out there I have at least one, or it's a kit I wouldn't want. They always say "why do you want two of the same kit?" I come back with " You go to a 1:1 car show and see 3 or 4 '69 Camaros, None of them are the same."
I have around 500 kits, I have plans for every one of 'em, whether I'll build it or use it for parts.
My wife thinks I'm crazy, but at least I'm home.