I love this plugin. Especially that I can compare two libraries by Goodreads ID.
I have a request for further development of this plugin. I would love to see it compare two libraries by series, not index number, just series. So if library A had books Alex Delaware  and Alex Delaware  and library B had had Alex Delaware  and Alex Delaware , they would all come back as a match. This would be so helpful for me. Just a thought.
Again thank you for developing Calibre and all of the amazing plugins that go with it.