What is considered duplicate and what is not?
Duplicate content is when the same content exists on more than one web page. Most search engines will attempt to display only one version, thus penalizing the other copies. While there is no strict definition on what is duplicate content and what isn't, it is generally accepted that the more unique your content the more it is favored by search engines. Google offers webmasters guidelines on how to avoid duplicate content penalties. http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66359