Duplicates images in Photos app
I've noticed that my Mac Mini automatically imports photos from my iPhone 11, but when I later plug my iPhone into the Mac (to delete images and clear up space), all of the previously (auto) imported images are still there in the Import All New Items list. If I hit Import (with the Delete after Import option on), I end up with duplicate copies in my Mac photo library.
The issue seems to be that when Photos on the Mac automatically imports images from the iPhone, it doesn't delete them from the iPhone.
Or is it maybe a symptom of the iCloud/My Photo Stream function? Do I have a fouled up preference somewhere? Or am I missing something obvious?