Google Dupes Its Directory Content

The Google version of the Open Directory - DMOZ.org - has always "lived" at directory.google.com, which is why I was surprised to notice today that Google has in fact duplicated its directory contents via the WWW subdomain:

A google search for site:directory.google.com yields approximately 1,300,000 results while site:www.google.com/Top/ pulls up a respectable 995,000 pages.



Recent speculation has suggested that Google is trying to nullify PR transfer from directories - but could the answer be as simple as a duplicate content penalty?