By default, if the file you are importing has a first field that matches one of the existing notes in your collection and that existing note is the same type as the type you’re importing, the existing note’s other fields will be updated based on content of the imported file. A drop-down box in the import screen allows you to change this behaviour, to either ignore duplicates completely, or import them as new notes instead of updating existing ones.
Except, there is no import screen. After choosing the .apkg file, importing starts straight away. After the import is finished, the info-window says:
Notes that could not be imported as note type has changed: 7845
That’s a lot of notes; I’d like to import them anyway, if need be as copies…