Seems like a normal workflow to me. When I import my pictures from my camera, I import them into a "year" project and a "year-month" album. That become their default "location" in Aperture. However as I arrange my pictures, I want to move them into other projects and albums. Because of the way Aperture use projects and albums, this is not an easy task:
I want to move picture P from Album A1 in project P1 to Project P2.
- Drag the picture P from Album A1 to Project P2
- Aperture will issue a warning: "You are about to move one or more master images to a different project. References to them will be maintained in any album that include them". Click "move".
- Aperture will move the master from P1 to P2. Aperture will copy the version from A1, leaving a copy in A1.
- You should immediately "remove from album" P from A1 to clear out the old version in the old album.