indyank - 3:42 pm on Sep 19, 2012 (gmt 0)

Exactly, most of the time these never existed urls are the result of their javascript crawlers that were introduced in 2011.They seem to discover or generate links by parsing the script and many times these result in these non-existent urls being generated and crawled resulting in 404 errors. I have discovered this way back in march 2011.

But be careful with http://example.com/some-slug-here/1345876986000 formats in wordpress as it will actually return 200 OK with the content of http://example.com/some-slug-here/.The best way to address this is by using canonical urls.