Redundant audio saved with project (and how to remove it)

I tend to write music by recording lots of short sections before arranging some of them into something resembling a song, and then break that out into a separate track to work on.

I had thought that the easiest way to do this was to duplicate the project, and then delete the unwanted bits from each of the 2 copies. (ie. Remove the song from one, and everything but the song from the other.) Unfortunately, Sonar doesn't seem to notice that half of the audio in each of the projects is no longer needed, so it sits in the project's Audio directory unnecessarily taking up space.

Is there a way to fix this? I saw 'Consolidate Project Audio' in the menu but the dialog box that comes up when you select it seems to imply this is for some other purpose such as backups.

Utilities/Clean Audio Folder