g1smd - 11:07 am on Aug 27, 2006 (gmt 0)

Be careful what you mean by "page". To me a "page" of content can have multiple URLs if there is an error in the site design. The optimum is for each "page" to be indexed once with just one URL that can be used to access it. What often happens is that a "page" gets indexed with multiple URLs - and then you are in trouble. The alternatives steal PageRank, turn supplemental, and their cache ages so that it no longer matches the real on-page content.

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URLs that are supplemental and are for live pages that are returning a "200 OK" for searches based on current content, and which are a duplicate of some other URL with the same content (non-www and www, multiple domains, multiple dynamic parameters, http and https), all need to be fixed with a 301 redirect to that canonical URL.

Supplemental results that represent older content at the canonical URL, can be safely ignored.

Supplemental results which represent duplicate URLs, but have already been fixed using the redirect, can also be ignored.

In those cases the supplemental result will be dropped after a year.

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[google.com...]