Is there any addon that allows importing apkg files even if there are duplicate cards?

[dae]

Importing duplicate cards, or duplicating a deck

I’m using v ⁨2.1.56 (07fd88dd)⁩. I’d like to use a deck that I have built as the starting-place for another similar but not identical deck. I have tried to export the existing deck, in apkg and colpkg, and then import it into the new deck. This appears to delete the cards that were the basis of the export and import the ‘new’ ones in their stead, not … as I had hoped … import the identical cards into my new deck. Is there some way of importing duplicate cards into a new, empty, deck?