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Duplicate content doesn't tend to burn a website out unless there is aggressive scraping going on as well as other balck hat signals. It sounds like the bigger question you're asking is how can the site be made to have unique content when it, along with many others, are pulling the same MLS content. This was asked about a year ago here: http://moz.com/community/q/real-estate-mls-listings-does-google-consider-duplicate-content, and the general consensus remains the same: try to find a way to make your content unique.