Oh, don't get me wrong - I have no problem at all with having bought the Collection - it was a very nice way to sample all the models and answer a lot of questions I'd had about them. It's in tribute to how good they are that I bought the rest of the sets. Strictly my choice, and I'm sure I could have had a good time with the Collection models and some repaints, as others had suggested. Would probably have done that if my Australian PC Aviator friends hadn't made it so easy to cross the line.
My current duplicates come, I think, from within the regular sets. For example, if I'm reconstructing it correctly, there's a WWII Happy Jack's Go Buggy in the Then and Now set and also in one of the others (Little Friends? sorry, I don't have the full list in front of me but you know what I mean). Since those are in different folders, they read as different aircraft, and Then and Now installation doesn't overwrite the other install. Not an issue by any means and it only affects a handful among dozens and dozens of versions. So I'm good.
Added benefit of buying the regular sets - I was able to do a no-tweak install of the B model of Short Fuse Sallee, which as Jankees knows is a particular devotion of mine.
So at the end of the day, I'm a happy though somewhat impoverished camper...