What pistol do you own duplicate(s) of?
And what is the reason? Variations? Paranoia about parts? You carry twins? Another for a significant other? Competition backup?
For me it is the Walther PPS, my EDC. I own 4 and all sport the Limbsaver 12012. A standard black .40 with laser sight (my EDC in an Ace pocket holster with the shortest flush mag), an OD .40, an OD 9mm with night sites, and a blaugrau 9mm. Sometimes I carry spare PPS's in my boot tops.