Many thanks for the response. Sounds painful, but I guess I'll just have to bite the bullet. I had already downloaded CCFtools and decompiled, but I was hoping for an easier way to at least eliminate unreferenced images. ISTR that one of the CCF editors was supposed to automatically eliminate unreferenced images on storing, but maybe that was just wishful thinking.
Some of the duplicates are actually slightly different colored versions of the same images resulting from bringing new CHAD gallery panels into my "upconverted" CCF file. The Tonto color conversion which was originally applied does not seem to affect these laterr additions.
You recommend using the CSF file produced by CCFdecode. Is there a reason why you prefer this to the XML file?