I am sure someone here can explain a bit better than me, but I experience this all the time with my site when I type "site:www.johninjapan.com" in google, then click to about page 20 and you will get the following message:
In order to show you the most relevant results, we have omitted some entries very similar to the 198 already displayed.
If you like, you can repeat the search with the omitted results included.
Google thinks that it is duplicate content, but it's probably my CMS and my poor Open-SEF implimentation. At least, when I hear duplicate content, that's what I consider it to be.
