determining whether font files are identical or differ using a shell script

I support 8 computers belonging to graphic artists which have a font train wreck. Over the years, the artists have stuck fonts in their ~/Library/Fonts and /Library/Fonts willy-nilly. They have traded around single files to get fonts they have needed on different computers. On a single computer they will have exactly the same fonts appearing multiple times in the two directories, and also the same fonts appearing more than once in files with slightly different names, as well as the same fonts appearing in multiple formats on the same machine, sometimes with the same version, sometimes with different versions.

And they have a LOT of fonts -- thousands of fonts in several thousand files each. Different files appear to be "broken" on the various machines. (And when I use the FontBook Validate Fonts and Validate Files, it gives me different errors for different runs.)

As a first pass I am trying to identify the files which are appearing on more than one of those 16 directories, and whether files appearing in different places are the same or different. In the Finder, I can see version information & file sizes, and can see whether they are the same or different for files with the same name. I thought that the command 'diff -rs' would tell me same/different, but I have just realized that all of the Font Suitcase files look identical to diff. And in fact they look empty to diff (diff reports that each one is identical to /dev/null.)

Is there any command which can identify same/different font suitcase files from the command line?