I don't know the answer to your question but I do know that as long as you (I) use a blogging platform to present material to the web, it's going to be with us.
I have two blogs. One is tamed down because I have an IRL stalker. I throw "Rebecca of Sunnybrook Farms" articles on it. On the other, I throw greatly edited versions of the first posts, speaking my mind firmly and clearly. I might be getting tagged for having duplicate content, too. But, as long as that guy is around to give me grief, that's the way things will have to be.
My advice? Just keep writing great original content that doesn't match up too closely with material on another domain. I'm of the opinion that Google has figured out how WordPress works, can identify it and a half-dozen other blogging / CM systems and can account reasonably well for the inherent duplications.