!Moving Photos to Trash in "Photo Library"
!Step 1: Switch to Photos application and choose Show Sidebar in the menu View.
!Moving Photos to Trash in "Photo Library"
!Step 2: The photos will be moved to the album named "Trash (Duplicate Finder Results)".
!Moving Photos to Trash in "Photo Library"
!Step 3: Select all and right click "Delect Photos"
!Next
!Launch Photos
!Don't show again.