Sometimes we definitely want 'items' though, so for example I am in a physical bookstore and see a book I might be interested in, so I buy it, to find out later back home that I already have the very same book - and edition - already. It's a scenario that anyone with some amount of books definitely encountered multiple times, I know I did it myself a few times. :)

Ability of an ISBN search of my collection would have helped me in this case - scanning a barcode is easy enough task to accomplish.

And even if I had a different edition, the resulting title from searching for a different edition would be enough to help me figure out that I should not buy a book I already own.