Yes! Got it! You are absolutely right, I read the report in the wrong order! Here is how the reports listed the duplicate pages:
http://www.virtualsheetmusic.com/score/PatrickCollectionFlPf.html?tab=mp3
http://www.virtualsheetmusic.com/score/PatrickCollectionFlPf.html?tab=pdf
http://www.virtualsheetmusic.com/score/PatrickCollectionVcPf.html?tab=mp3
http://www.virtualsheetmusic.com/score/PatrickCollectionVcPf.html?tab=pdf
So, I thought the first couple above was a duplicate, and the second couple the second duplicate, instead here are the right coupled duplicate pages:
http://www.virtualsheetmusic.com/score/PatrickCollectionFlPf.html?tab=mp3
http://www.virtualsheetmusic.com/score/PatrickCollectionVcPf.html?tab=mp3
and the second couple:
http://www.virtualsheetmusic.com/score/PatrickCollectionFlPf.html?tab=pdf
http://www.virtualsheetmusic.com/score/PatrickCollectionVcPf.html?tab=pdf
So, I agree that the SEOmoz duplicate report should be improved graphically to avoid such a kind of confusion.
And that kind of duplicate issue is actually something that I might need to fix on my part... but with the fact that both duplicate pages belong to two different items and have two different canonical definitions may possibly solve the problem by itself... or not? I guess this is one of those rare cases where SEs can actually get confused!
What would you suggest to do with this kind of cross-similar product pages? Those are legitimate pages belonging to two different items that have the same kind of content (i.e. same included music pieces) but written for different instruments! And here is, in fact, another thread where I am discussing about how to handle these kind of similar products found often in the music industry, where the same piece of music can be written for several different instruments causing nearly-duplicate pages:
http://www.seomoz.org/q/canonical-tag-how-to-deal-with-product-variations-in-the-music-industry
Any further thoughts are very welcome.
Thank you again Dr. Meyers!