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It sounds like you may be misunderstanding what a duplicate content penalty might be. That usually happens when you wholesale scrape other sites and don't have any unique content of your own. Syndicated RSS feed content wrapped within your own content should not incur the wrath of the SEs.
i just cant see how they will rank a page when it is scraped - also do they just show a snippet - I suppose that a snippet would hold - but of course you just then send the viewer offsite to view the full thing.
You'll of course want to have some good content of your own. That's when you can run your own RSS feeds and hopefully have others use (and link back to) your content.