[Starson17]

Originally Posted by unboggling

A couple months ago I mentioned I was losing some books occasionally during Save/Add operations to populate new empty libraries, with Automerge off, and Yes to add duplicates.

As an aside (that you probably already know), at about that time there was a similar issue with Automerge on when combined with Copy to Library with deletion from the source library. Changes were made to the CTL code at that time.

I finally pinned down this behavior. It happens in Save To Disk from Library 1, not in Add Books to Library 2. Add Books can't find what Save To Disk didn't put there.

In two separate records, if Authors matches Authors AND Title matches Title, one of those records is dropped during the Save To Disk. This happens when the Authors and Title combinations are identical, independently of any other fields, including IDs. For example, 2 books are both Saved when they have identical ISBN13s and unique Authors or unique Title; but 2 books are not Saved when Authors/Title combination keys aren't unique even when their ISBN13s are unique.

I was able to replicate this when the Save to Disk template includes only the {authors} and {title} fields. In that case, it's trying to create two books with identical names. I think it should probably be fixed to produce an error message, and/or offer to modify the names to make them unique. I'd suggest adding a bug report to at least make a record of the issue.

Copy To Library does NOT have this behavior, it Copies both records when their Authors/Title match.

Correct (mostly). If Automerge is off, it will see this as a Duplicate and ask if you want to add the duplicate book. If Automerge is on, it will obey the options for Automerge (one of which is to silently ignore the duplicate).

This isn't necessarily a bug with Save To Disk, but it's something to keep in mind.

It should probably at least give a warning.

The work-around for Save To Disk is: within any particular Authors, append something different to identical Titles to make each Title unique, such as "(from Amazon)" on one and "(from Gutenberg)" on the other. Or, use Copy To Library from Library 1 to Library 2, rather than a Save To Disk from Library 1 followed by an Add Books to Library 2.

Another workaround would be to make sure your save template has a unique field for the name or folder. You could add a column for version number, only populate that field when you have multiple versions, and use a save template that ignores that field unless it's populated.