Moving Photos Between Album

I'm having difficulty with moving photos between albums.

I moved photos from the original album into two new albums. Now the photos are still in the original album, and also in the new ones. Does that mean they're duplicated? Do I need to delete them from the original? Is there a way to actually move them between albums and not duplicate them in one step?

And why does the site say I "posted new photos", for the photos that I just moved?