[SergioR]

I would like to know if anyone is aware of the comparison process that Calibre performs when an EPUB file is uploaded to the Calibre library and it detects that the file already exists.

In other words, is the initial duplicate check based on the
1) file name,
2) the book’s title and author,
3) or the file’s unique hash?

The latter would be the only method that actually guarantees the book (file) is a true duplicate.

Thank you all for your attention, and thanks in advance to anyone who can help clarify this doubt.

SR