As I have been discussing this subject recently I thought it would be a good idea to publish this video which has been produced by Google who have also been discussing the same subject and advising on what to do about inadvertent production of duplicate content.
The video also covers the implementation of the new rel=canonical tag which can be used to identify content that has been duplicated deliberately on a single domain.
Most importantly though, it does confirm that the duplicate content penalty is a MYTH
The answer to the above question is relatively straight forward and is a little like cholesterol. There is good and bad duplicate content.
