To recreate: - Have a bib in your system with the title "E Street Shuffle" - Confirm you do not have barcode "XXX" in your system - Have Fast Cataloging enabled - Try to check out barcode "XXX" to a patron, get notice that barcode does not exist, follow link to Fast Cataloging - In your Fast Add record, enter title "E Street Shuffle" - click Save, get a popup asking if your new record is a duplicate of the existing record - click "Yes, View Existing Items" - Koha takes you to the existing bib, where you can add a new item (assuming you have permission) - that item will not maintain the XXX barcode and will not follow any of the other settings in one's Fast Add framework I don't expect all libraries to agree on how this should work. It'd be great to have a system preference with which to set whether or not to do that dupe check at all on fast add.