Why do we buy duplicates?

[Ankerson]

I get them to have either a backup to a user in case something happens to it or one to use and the other for the safe.

 

[PKFan]

I've done it for a couple of reasons. Like others have said, it may go out of production (read "Spyderco"). Another reason is to outfit bugout/get home bags for multiple vehicles/uses and I found a reasonably priced performer to put in each (Kershaw Skyline). Or I just got a good deal and had to buy more than one (who *needs* 3 black mini-grips?).