"They are not duplicate sites they are someone elses domains pointed at Alans website, and registered in Google as such. I tested this by changing some text to Alans website and testing their domains in a browser instantly, and the changed text was showing. "
the above from the horses mouth

I'd say yes it does matter he seems to be saying someone is mirroring content with an instant update and pointing it at his client. Been there and done that and it will have exactly the affect Alan describes. I did that when I left a personal account on my ISP. I thought I'd just link from there to the new domain Tsworldofdesign.com. Nope absolutely the stupidest thing I've ever done. Tsworld was buried on G but the old site continued to place for years.

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