Thanks! For the time being I have added numbers in square brackets to the tile as a quick solution. I think the marking feature will not be needed once the planned algorithm is implemented (I understand it will allow users to define which fields one wants to take into account when detecting duplicates). Many thanks!

I was just guessing. I think it would be useful to allow users select the fields to be taken into account -- but not knowing how the new algorithm will work, I will not insist on it :-)

mark: Thanks -- I should have found it before asking the question :-)

jaymanxv: Are you saying those two items are identified as duplicates in the Duplicates view? Do they have the same DOI?

In my opinion, items should only be considered as duplicates by Zotero if

- title
- author(s), editor(s), etc.
- volume

are the same.

If you want to have different volumes of the same encyclopedia in your library, at the moment, they will all show up as duplicates because the title is obviously the same.

Being able to define the criteria for qualification as duplicate myself would be perfect, but the above mentioned would already make the feature much more useful for me and is much easier to implement, I guess.

I am having trouble with this. I am getting different volumes of Knuth's art of computer programming marked as duplicates. Is there anything I can do?

Zotero seems especially inaccurate with magazine articles, which don't have DOIs or ISBNs. If anonymously authored, matching titles and years alone cause Zotero to think they're duplicates. Consider these film reviews:

“Alice in Wonderland.” Life, vol. 30, June 1951, pp. 85–87.
“Alice in Wonderland.” Library Journal, vol. 76, Aug. 1951, p. 1239.

Zotero marks these and 10 more like them to be duplicates.

Is there any reason that it would be a bad strategy for Zotero to require matching publication title to mark articles as a duplicate?

@paulvdh, here's the duplicate criteria:
"Zotero currently uses the the title, DOI, and ISBN fields to determine duplicates. If these fields match (or are absent), Zotero also compares the years of publication (if they are within a year of each other) and author/creator lists (if at least one author last name plus first initial matches) to determine duplicates. The algorithm will be improved in the future to incorporate other fields."

So only info in those fields would affect the duplicate evaluation.

I feel the same way as mark. If the library is big enough you will have a hard time to determine the real duplicates in the big bunch of elements marked falsely as duplicates.

An option to to mark a "false duplicates" as a "non duplicates" would be a great relieve fo me as well.

Making this problem worse is the fact that a PhD thesis does not have DOI or ISBN fields. But a thesis which has a corresponding journal article of the same type, by the same author, in about the same year, is an extremely common thing.

Yup, just to update my estimate from 4 years back: I now have aboug 235 items in my "Duplicates" pane that are not, in fact, duplicates and so it's only become harder to spot genuine new duplicates.

@qqbb I acknowledge the potential issues of marking items as "false duplicates". However, many "false duplicates" can be readily handled even if without this function. I would request to improve the detection mechanism so that it will be able to introduce much fewer "false duplicates". For example, for book collections which are formatted as books somehow in some database, all these papers will be recongonized as duplicates, even if they clearly have different titles and authors. This is one of the major causes of false duplicates for my case, which is also most difficult to handle.

I'm not sure why the detection mechanism is designed in such a way, and I have raised this issue in 2019 and somehow this issue still persists, even though it seems trivial to me to change its detection mechanism to handle this issue.

The reason that I come back to this issue is that, I found some plugin that can merge the items in the duplicates folder in batch, but the existence of the false duplicates, especially those conference papers with different titles, makes the job quite cumbersome.

For my case, I occasionally do literature reviews on different topics, and hence, I need to import the relevant papers at different times. Many times, some duplicates will be imported. If the false duplcates issue can be solved, that would save me a lot of time of manually cleaning up the library, or from suffering of have different versions of the same paper.

I regard this as a fundamental function of a database management software, because importing data is the beginning of everything. If possible, I hope that the team would consider giving higher priority to this issue.

another possible solution is to provide the users an interface to append customized rules to the detection mechanism, to handle the issues one may encounter.

Although there's a degree of fuzziness in the definition of some item types, and the web plugin in particular may not choose the correct one depending on the source page, type is still a reasonably strong predictor of whether or not two items are the same. Zotero even recognizes this to the extent that items all have to be of the same type in order to be merged. So it seems especially silly not to provide any way to stop suggesting a merge when the user knows the items are correct as is and not merge-eligible. I have a lot of items that are different manifestations of the same work (e.g.. a conference presentation and its published version), or related works by the same author with the same or similar titles (e.g., a dissertation chapter published as a journal article, the completed dissertation, and a later book). Not all of these can have ISBNs or DOIs, but they're all different types. Insistance on keeping these things in the list of duplicates makes the process of seeing and resolving real duplicates harder. Giving users the choice to edit the criteria for determining duplicates would solve this.

Just revisiting to note that there are still 230 items listed in my 'duplicate items' that are all non-resolvable non-duplicates with item type differences, making the duplicate items impossible to navigate and nearly useless...

I'm pretty sure there's been work on marking items as non-duplicates in the last 6 months, yes.
I've not seen anything on improving the detection algorithm (or allowing some level of customization) but that doesn't mean no one is thinking about it, just that there isn't any public code.