When I create a new album it automatically imports all the photos already imported into the whole folder

I am creating a new set of albums in a new folder and importing photos by dragging them from the folder in Finder, and dropping them into the new album. Mostly works a treat. BUT when I try to create a new album it immediately imports all the photos already imported into the albums in that Photos FOLDER. I want to add perhaps a couple of photos and there are 200 already in the album. Driving me crazy.

I note that the shortcut to creat new album now always says 'New Abum with selection'.

I will attach a screen shot of this, the number of selected happens to be 2 in this instance but could be 300 or anything that is already imported. The only way forward is to delete the photos, and delete the album, then repeat the whole process.

What can I do to avoid this automatic duplication? Life's too short for this.