When you copy a photo, or a series of photos, from one folder to another, it is displayed in duplicate in the destination folder in “photo library” mode while it is present in only one copy in the “Finder”. This happens whether you do “option” + “click-move” on the same disk, or simply “drag and drop” from one volume to another in the “photo library”.
Deleting only one of the two identical thumbnails deletes the photo from the destination folder and triggers the appearance of a "? "In the “Photo Library”
. The only solution to restore the image is to take it out of the trash to the destination folder.
Had a look at the issue with DPL 7.1.0 on macOS 12.7.1 - and found two representations in the target folder.
Checking image properties with command-I, I found that
one image has been copied to the target folder indeed
the second appearance is listed as residing in the original folder
the source folder shows as one image short
images as displayed by Finder have been copied correctly
This means that DPL displays the images as having been moved instead of having been copied.
Moving a file to the target and back fixes the appearance of images in the source folder, but the target folder still shows two copies instead of one.
Deleting the copied file in DPL des not fix things, but after *moving the “fake” copy from target to e.g. Desktop and then to source seems to do the trick
BE EXTRA CAREFUL WHICH FILE/IMAGE YOU DELETE UNDER THESE CONDITIONS!