Matt Cutts answers a question about duplicate content in his latest webmaster help video where a user writes in to ask “If you had to deal with short-term duplicated content on a news site (perhaps publishing a story on two different URLs over one day), what would you do in order to avoid any penalty from a duplicate content filter?”
Google’s major search engine function is to offer a customer the best possible results for a search, based upon the search term (keywords) that the customer has used in the Google search box. While the story is breaking Matt says it’s understandable that you’ll have multiple instances of that story spread across the web. When things settle down, having a “rel=canonical” tag in place indicates the preferred location on the web where you would like that information to sit.
Cutts also did say that 25% of the web is duplicative, so you really don’t have to worry about it.
For more information to the question in his own words, see the video below:



