I have had this happen as well. I am assuming it is normal since all of the clubs are in Titleist's database. If you put in the SN and got a completely different club that would raise a red flag for me.

It's been my experience that with the amount of clubs they produce, that some serial numbers are duplicated but only across generations. You would not find the same serial number in the same generation of irons for example. I believe that you're fine if you see the correct club, then some older ones.

I do believe the serial numbers eventually recirculate. Their purpose is to track your warranty and therefore after the warranty expires, their usefulness diminishes. Some people think they help verify authenticity but serial numbers can easily be copied so unless they track by name to the original owner and that is who you purchased it from, it’s no guarantee it is the exact same club.

Sounds like at least 1 is bogus. If you didn’t get your driver new through an authorized dealer, you might want to follow the chain of custody. The internet is notoriously bad for bad products.