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On this e-commerce site, there are sections (like "blue widgets" and "red widgets") that have multiple pages (like "blue widgets - page 1," "blue widgets - page 3," etc.) but because they are all the same section, they all have the same meta titles and descriptions.
Anybody else seeing sudden issues like this in WMT?
On lower PR pages, having a unique title and a unique description that are specific to the page content can make the difference between getting SOME search traffic to that page versus getting none at all. Low PR pages don't seem to get the "full treatment" from Google, but just something like a quick tagging of a few key page elements. Remnants of the old Supplemental Index system, I think.
And the dupe content filter does not knock pages out of the index. It is a run-time filter that affects the SERPs as they are served: If two candidate results that are to appear on the same results page have the same title and snippet, the lower ranking page will be knocked to the next results page.