I have "close" duplicates of some guns - same gun, different configuration - just for the fun of it and because I like them. I do have a couple models where I have squirreled away exact duplicates.
Why? I found that they fill an exact nitch - and fill it very well, at least for me. And then the model gets discontinued.
The Beretta Model 70s in .22 is an example. Great back pocket field gun for small game. Unfortunately(?) the first one has outlasted my eyes - but just in case it hadn't, I'd put a couple of extras back when they were discontinued.
The Rem. Nylon 66 is another example. The Apache Black model with the chromed barrel/receiver. Drug one all over Alaska for three decades. Extreme cold, wet, dirty - whatever - it always came through. They've been history for a while now, but just in case my original goes belly up, I have a couple of extra put back.
I have another trio that is just hapenstance. Years ago a dealer was going out of business and had some Ruger 77/22s (with sights) at one hell of a discount. I got 3 of them. One for me, one for my father and one that I'd planned on giving as a gift. Never did give the third one away and after my father died, number two came back. One of these days I'll run across some youngster or two that deserves one. In the meantime they are paid for and don't eat anything.
The Berettas and the Remingtons were relatively low budget guns, but they struck a cord with me - and just fit the use to which I put them.
The Ruger 77/22 does as well, but they still make those. If Ruger drops that model tomorrow, maybe one of those will stay tucked away.