FBA unfulfillable item returned but it’s not my item.

It’s not worth fighting because it’s less than £10, but I’m curious why this has happened.

Sent in 10 items to FBA, one of them was unfulfillable and I chose to have it shipped back to me. The item arrived and I can see why it is unfulfillable, it is the same item but it doesn’t have it’s packaging, it’s just loose inside plain transparent packaging with an FBA label which is not my label.

How has this happened? It looks like an Amazon Warehouse item where they sell items with damaged or no packaging. The FBA label is not mine, it’s a completely different sized label to what I use.