Photos will tell you that a photo is already imported, if the photos are still in the Recently Deleted album.
You do not need to delete the imported photos from your Photos library to add them to a different album. The albums are not storing the photos, just referencing them. You can add the photos to as many albums as you want, without
Try this:
- Open the Recently Deleted album and select the recently imported photos together and use the command "Put Back".
- Now open the album where you do not want the photos to appear, select all photos there, that you want to remove together, then do two things:
- First add them to the album, where you want them: With the photos selected, use the command "Image > Add to" then select the album you want or use "New" to create the new album. Or simply drag the photos from the current album to the destination album in the sidebar.
- Then remove the selected photos from the album, where you not want them by pressing the delete key ⌫. Or use the command "Image > remove ... photos from album".
It is not possible to move photos directly from one album to another, as the albums do not store photos, just show them by referencing the one copy of the photo in the library. So we have two do it in two steps, first add the photos to a different album, then remove them from the albums where we do not want them to be shown. Most of my photos are in many albums, as I am creating albums mainly for the projects I am working on, so my best best photos are needed in for several projects and thus are in several albums.