and since all blogs have different keywords and unique names it not going to really be that much of an issue we don't think..
if some one was searching for "x-rated nudes" they might find an entry on Simon's blog but they could also find the same entry when searching for "foxy nudes" might end up at Sue's.
there are so many variables and like oast said, lots of news feeds go everywhere every day, and as long as there is some other relevant text with in the blog it won't be the same.
But then again the way google has acted stranger things have happened.