Frequently when researching an issue I find references I want to keep without taking the time to determine whether I already have them in my 18,000 item database, resulting in duplicates.

I prefer to have one entry for each distinct reference.

Zotero is good at identifying the duplicates (albeit a little too late, see another entry here). But all it offers is to merge them. Commonly, I would rather simply delete the newer entry as I may have enhanced the one I have already. For instance, I typically create a link to a separately stored pdf if I have it. I prefer to link, rather than incorporate, the pdf, to keep the size of my database manageable. If I merge the items, I have to choose between the versions, which requires inspection in detail that takes too much time.

If the Duplicate Items view allowed me to select one or the other of a pair, I could easily identify the one to delete by its Date Added. But, if I select either, I get both. And, in any case, deletion is not an action supported in this view. If the Duplicate Items view allowed me to select everything, I'd drag it all to a new temporary collection, sort by Date Added and do a mass deletion there. But, although I can highlight everything in the view, if I try to drag it all, instead the selection is decreased to the first pair. And, in any case, dragging and dropping is another functionality not supported by the Duplicate Items view.

I don't expect any user to have a solution for this. This amounts to an enhancement request to the developers.