g1smd - 2:55 am on Sep 13, 2008 (gmt 0)

*** Externally linked domains carrying the same content has been detected for some time. ***

Yes they have, and that's a whole different story.

I doubt, in those cases, that they re-assign back-links that point to resource X and count them as if they actually pointed to resource Y.

Or do they?

It would seem a bit risky to take things that far, but on the other hand, it might explain the catastrophic drop in performance when another resource is named as the original.

So far, in my post above I was only thinking about URL variations and duplication within one domain - and maybe that is all the Google announcement was thinking about too, and we're reading too much into it.