Item Duplication

Somehow a unique trinket was duplicated in my inventory. I sold a [Figurine - Jade Owl] to a vendor. Then awhile later, I had 4 of them in my bags.

I am not sure how it happened. This seems crazy because the trinket is Unique so I shouldn’t be able to have more than 1 on me.

This happened a few days ago on my TBC character Frostdoctor.