I'm not sure about the algorithm in use, but I what I hope is happening is that Google is now looking for the earliest publication of content when deduplicating

I'm not sure about the algorithm in use, but I what I hope is happening is that Google is now looking for the earliest publication of content when deduplicating. Most copycat sites have to copy their text from something existing, and if Google has already indexed that, they know that later versions of it are copies (and can presumably be knocked down in rank).