Scan entire blog for duplicate content?

Does anyone know if there is a tool out there that will scan an entire website for duplicate content. I know the paid version of copyscape will, but there must be a free alternative. Scanning one page at a time is far too slow.

How many pages have you got?

I found doing it manually in google is faster than most scanners, but yeah that depends on how many pages on your site.

this is another good one similar to copyscape, not sure if its automated enough for you though: http://plagiarisma.net/

Some more listed here too, but again I dont think there is one that will scan an entire site: http://blueblots.com/tools/15-tools-for-checking-duplicate-content/