Google will not penalize you and this myth has been going on for a couple of years now. I have looked in their TOS and spoken to professionals in the search marketing industry. Basically you can create duplicate content across multiple blogs but what will happen is the less desired result will fall in the index and not be ranked as high. Some cases the duplicate content can be removed from the index if Google feels it was made to deceive or manipulate its users. However the myth of your site being banned is not true.
If you look at the online news agencies that syndicate content from the associated press or sites that get online press releases from distribution sites, they share tons of duplicate content and nothing has happened to them. It is just that some content will rank high based on relevancy of the content and the ranking of the site itself with Google. I hope that was clear. If not just tweet me and I'll explain further.
Although I don't think you are penalized only one may show up in searches and/or track the stats of the blog. I'm just jumping into multi blogging myself and highly suggest, if you are not already, becoming a member of Active Rain. There is just sooo much blogging and SEO information available on AR. http://activerain.com/action/referrals/gc1023
Another article that may help you is: http://www.ninebyblue.com/blog/ranking-as-the-original-sourc
Keller Williams Atlantic Shore