Hi Pratyush, thank you for your answer.
Of course, it only helps to a very limited extent, with 1400 entries: Find and delete duplicates manually, entry by entry ...
But good if you have backups:
Delete the vault, create a new vault, import the data again, restore the sync, then delete the vault on all devices + restore the sync.
This is probably the reason why so many people here in the forum would like to have the FIND + REMOVE DUPLICATES feature
Happy holidays
Frank