I bought a bunch of books from the local library, stuff they were removing from the collection, and I'm kind of confused about how their process works.

They're not labelled as 'removed from collection', they still have the original inlay and RFID tag, they're indistinguishable from regular borrowable works in every way that I can identify, and they didn't scan them to sell them to me either - they just counted them and multiplied them by 1.50 EUR.

I have absolutely *no idea* how they are preventing these books from getting mixed up with the rest of the collection, whether unintentionally or otherwise.