This additional idea comes from my experience reimporting a whole Pass dataset, hoping it would replace existing items and update them.

Each item should have additional metadata, such as an import ID and import date-time, perhaps the date-time could be encoded into the import ID. The way this would work is, that at the time of import, an auto-generated import ID would be created for any and all of the imported items, so that multiple items, being part of a package, imported in bulk simultaneously, would share the same import ID and date-time of import.

This would allow for more advanced filtering and management, which would allow for an extremely convenient way to revert and undo a potentially mistaken import in just one action, without having to manually inspect or select in case there are duplicates or other conflicts.

Otherwise, items would have another value for the import ID parameter, perhaps a special fixed reserved GUID/HASH, indicating that they did not come from an import and were generated, either by the user manually, or by proton-pass auto-suggestion automatically, which would use yet another special reserved GUID/HASH, for example.

I was also wondering first about an "export ID" being generated when exporting to ProtonPass JSON could have an "export ID" and that export ID used for what could be the import ID ... but the import ID idea above is probably better and enough and covers all other types of imports, not just my specific case of reimporting an exported ProtonPass JSON (trying to bulk edit and hoping it would replace existing entries ... it made duplicates because this kind of trick isn't supported yet)

Currently the only way to figure out duplicates by metadata is to check history, that is only if the original didn't have history.

ProtonPass own JSON export doesn't include exporting history, when reimporting, the creation date of the duplicated item is the same as with the original, but when viewing it's history the "current version" modification date is the only one and the same as the original item unless the original was ofcourse modified later.

However there's no way to search, filter, sort by metadata at all (dates, ids, modification count, etc)

Also Aliases work different ... I didn't dig into that yet, it didn't import or duplicate anything for me

Also, this feature depends on this: https://protonmail.uservoice.com/forums/953584-proton-pass/suggestions/49324517-ability-to-also-filter-by-item-metadata-ids-date