How can I duplicate a photo that's in a shared folder?

A colleague created a shared album and shared it with me. In the album is a photo that I would like to duplicate and resize (so it doesn't alter the original). Problem is... "duplicate" is greyed out. Any ideas? 

As a workaround I was thinking I could add it to a different folder and edit from there. But the option "add photo to album" is greyed out too.... 😞