Every reader has done it at least once. You spot a book you're sure you don't own, carry it to the till, bring it home, and find its twin already on the shelf. A duplicate is a small, specific kind of heartbreak: money spent, shelf space lost, and quiet proof that your collection has outgrown your memory. The fix takes about ten seconds.
Step 1. Scan it before you buy
Standing in the shop, open the scanner and point it at the barcode on the back cover. oobookoo checks the book against your whole catalogue and tells you on the spot whether it's already on your shelves. No barcode on an older copy? Move to step two.
Step 2. Search by title or author
For secondhand finds, signed copies, or anything published before barcodes, open Catalogue Search and type the title or author. Your library answers instantly, so you know whether that tempting green hardback is a real gap in your collection or a copy you already own in a different edition.
Step 3. Keep your catalogue current
A check is only as good as the library behind it. The faster you add books, the more you can trust the answer, which is why the photo Shelf Scan matters: one picture adds up to fifty titles, so your catalogue keeps pace with your shelves and the duplicate check never lies to you.
Why it's worth it
Buying a duplicate isn't really about the few pounds. It's the feeling of not knowing your own collection. A library you can check from the aisle turns guesswork into certainty, and lets you buy knowing that every book you carry home is genuinely new to your shelves. Unless, of course, you meant to buy a second copy for a friend.
Know before you buy. oobookoo is free to start, a home for the books you own.