Erroneous duplicate notification

[Fredrick]

I had problems with Calibre earlier this year and eventually uninstalled and reinstalled it. I started over with a new database, but when I add books, Calibre notifies me that I am adding duplicate files. This makes no sense, since it is a new database, right?

I have tried uninstalling Calibre again, searching all Calibre files that remain, deleting them and then reinstalling. Same problem. I've used the addition date for the nonexistent files as a search term. Nothing. Clearly, I am missing something. Anyone with advice on where I can look to find the leftover files that are causing this problem?

[itimpi]

I have found that you can get that message if the books you are adding contain the same book in more than one format.

[Fredrick]

Thanks for the suggestion, but the only format I have is .epub

[itimpi]

When you get the duplicate notification the you are given an option to see what titles are involved. That might help you identify the cause.

[fidvo]

I've noticed that the most common cause of this duplicate notification, at least for me, is when the metadata is wrong in the original book, specifically when the title and author fields are reversed. So when I add two books by the same author, Calibre sees them as two books with the same title by different authors and triggers the duplicate alert.

Hope this helps.

[theducks]

Originally Posted by fidvo

I've noticed that the most common cause of this duplicate notification, at least for me, is when the metadata is wrong in the original book, specifically when the title and author fields are reversed. So when I add two books by the same author, Calibre sees them as two books with the same title by different authors and triggers the duplicate alert.

Hope this helps.

In that case, Calibre is CORRECT. There is a duplicate.
(been there )

[Fredrick]

I tried adding another book and, again, received a message that I was adding a duplicate title. This is not so. Since I am adding author by author, no other books by any added author existed. I looked at the duplicate title message and found no way to determine what data source Calibre is using to determine that the title already exists in the library (which is untrue).

Each time I get this message, I add the book anyway. I then find that the title exists twice in the library (where it had not existed at all, previously). Both entries are identical, except that one entry shows the size of the file and the other has a blank field for file size. Clicking on the first file brings up the viewer with the functioning epub book displayed. Clicking on the second file brings up an error window that informs me that no such file exists. Which I knew.

The question is why does Calibre find a duplicate title where no such title appeared in the library previously. I would suspect that Calibre has a database file that was not deleted during the uninstall and the program is cross-referencing it.

With this in mind, I uninstalled Calibre again, then searched for all Calibre related files and deleted them. I did find a Calibre folder in users/(my name)/appdata/roaming and deleted it. Did not help. Any ideas where other post-uninstall Calibre files might be lurking?

[Adoby]

How do you add the books?

Is it possible that you add more than just a book?

What happens if you select just one single ebook and drag-and-drop it from the folder into calibre?

[Zetmolm]

When you add author by author and the metadata is wrong you can get exactly what fidvo said.

Also, do you use a recent release of Calibre? A couple of weeks ago the messages that you get for duplicates have been made more meaningful. Please upgrade if you did not do so yet.

[Fredrick]

Dragging and dropping worked great, which has lead me to suspect the Calibre is picking up opf files as ebooks. Is that possible? If so, is there a setting that will merge the opf and epub filess either as I add them or after they are added?

I am using the latest version of Calibre.

[kovidgoyal]

calibre does not treat opf files as ebooks.

[Fredrick]

Then I am lost. I just added two books by Rousseau. The directory structure was Rousseau/Emile and Rousseau/Confessions. Both subdirectories had an an opf file and an epub file. I used the third option (multiple books per directory, assumes every ebook file is a different book), because some of my author subdirectories have more than one book. I had no Rousseau books in Calibre.

I received notice that I was adding duplicate books and found that there were two entries for each book. One entry (for each book) was an actual epub file. The other entry (for each book) showed all the information for the book except size, but clicking on it revealed that there was no such book in the library. Following the paths for the null entries revealed two additional subdirectories for each book, both containing only an opf file.

[kovidgoyal]

The opf files are generated by calibre as metadata backups. They are not the opf files present in the import directories. Since you say drag and drop works for you, use that. I will take a look into whether adding OPF files with the multiple books per directory option causes problems when I have some time.

[Fredrick]

Thank you for your advice. Final question: since the null entry sometimes has better information than the actual entry, if there any way to merge the two?

[kovidgoyal]

I looked at it, and there was indeed a case where using add multiple books per directory could cause the OPF file to generate an extra book (a bit of code copy pasted from the single book per directory code path). Fix will be in next release. You can either wait for it, or just use drag n' drop, ignore the duplicate warnings, delete the opf files or add folders that contain opf files as single book per directory, which will allow calibre to preserve the metadata from the opf file.