Ask which kind of duplicate you mean
There are several different questions hidden inside “I already have this book.” You may mean the same work, the same edition and format, another physical copy, or an extra database entry for one copy. Decide which question you are answering before deleting anything. A reading record and an ownership record need not have the same granularity.
The International ISBN Agency explains that language editions, revised text and different product formats can need separate ISBNs; an unchanged reprint can retain one. That makes ISBN a useful publication clue, not a personal copy number. Keep any local copy ID separate from the ISBN field.
Inspect the actual book’s title/copyright pages and format. AI capture, cover similarity or a search result can suggest metadata but does not verify the specific object on your shelf. Leave missing publication details unknown until you check them.
Three physical books, four entries and one suspected record duplicate
This original example uses a fictional title, “Field Notes.” ISBN-A and ISBN-B below are placeholder labels, not valid ISBN numbers to enter into a catalog.
| Local copy / entry | Publication clue | Physical location | Interpretation |
|---|---|---|---|
| B01 / R1 | Field Notes paperback; ISBN-A checked | Shelf 1 | One physical copy |
| B02 / R2 | Same paperback; ISBN-A checked | Loan box | Second real copy; not an accidental record duplicate |
| B03 / R3 | Field Notes hardcover; ISBN-B checked | Shelf 2 | Different format; inspect edition details |
| B01? / R4 | Looks like R1; identity not checked | Unknown | Suspected duplicate record; do not merge yet |
The shelf check establishes three real copies. Four entries do not establish four copies, but neither do they justify immediate deletion of R4. Compare the source of the entry, notes, progress and any photo with B01. If R4 is confirmed to describe the same physical copy and purpose as R1, preserve any unique notes before deciding how to remove the duplicate.
If R4 instead describes another real copy, assign its own local ID and location. If you cannot tell, leave it unresolved. Do not erase uncertainty by assigning “Shelf 1” just because that is where the known paperback lives.
Preserve notes and edition context before consolidation
A page reference in the paperback may not locate the same passage in the hardcover or a revised edition. Keep enough publication context beside notes to recover the passage. The reading-notes guide is a useful next step after identifying which edition you used.
Compare title, author, language, format, publisher information and edition statement as available. A different ISBN is a reason to inspect the publication, not proof that the words or reading purpose must differ in every respect. A missing ISBN is not proof that two records describe the same item.
Do not put an internal shelf or copy code into the ISBN field. For older or unusual books without a usable ISBN, use truthful notes and your own reference outside that field. Keep a recoverable copy of unique progress or annotations before deleting a suspected duplicate entry. The aim is a clearer library, not the smallest possible count.
ReadCue captures editable metadata; verify the edition yourself
ReadCue’s current listing describes editable drafts with title, author, ISBN, categories, summary and confidence notes, plus reading status, pages/minutes and notes. Premium unlocks unlimited AI capture, voice/photo add, advanced stats and recommendations. Check current limits and consent details before using capture.
Current source has ISBN, language, notes and record IDs, but a complete edition/copy hierarchy, dedicated physical-location schema or automatic duplicate-merge workflow was not verified. This comparison sheet is an external companion. Record an appropriate short reference in notes if useful; do not assume the CSV imports or links copies automatically.
A high confidence note on a draft is not proof of an edition match. Check the actual publication and review the editable result before saving. ReadCue can organize your reading activity while the companion table makes the specific edition/copy question explicit. No library-catalog certification or automatic deduplication outcome is claimed.
If the method fits your task, explore Book Tracker: ReadCue’s listed features on an iPhone. Check current features and plans before downloading.
See Book Tracker: ReadCue for iOSDownload the free worksheet
Use the CSV in Numbers, Excel or a spreadsheet editor. The title and identifier labels are fictional; ISBN-A/B are not real ISBN values. Replace them with your own observations. The CSV is separate from the app and no email is required.
Questions answered
Do two identical ISBNs mean I should delete one entry?
No. You may own two physical copies. Check what each entry represents and preserve unique notes before changing records.
Can a paperback and hardcover have different ISBNs?
Yes. The International ISBN Agency identifies different product formats separately. Inspect the actual edition and format rather than relying only on the title.
Does ReadCue automatically merge duplicate editions?
A complete edition/copy grouping and merge workflow was not verified. Use manual review and the companion comparison.
Continue with Book Tracker: ReadCue on iOS
Use the App Store listing to check compatibility, privacy information and current plan terms. A free download may offer paid features.
Download Book Tracker: ReadCue for iOSSources and product details
- International ISBN Agency: ISBN assignmentPrimary rules for edition/language/format identifiers and unchanged reprints; not an identifier for your individual physical copy.
- Book Tracker: ReadCue on the App StoreCurrent US App Store product description; checked October 30, 2026.
Editorial method: primary guidance, a current Apple listing, an original worked example and an independent critique. No search ranking, install or outcome result is claimed.