[zaroth]

Even if you don't care about trying to identify the original source of some piece of content, it seems like the content farm site which is plagiarizing is more likely to be a lower quality site than the original content producer.

The behavior does seem weird in any case, like there is a certain slot for a given piece of content, and Google is swapping different domains in and out to fill that slot. It seems like Google is actually trying to identify the original content, failing, and then actually inadvertently penalizing the original producer.

[scholia]

Well, Google has already indexed a new article x. When article y appears, and Google sees that y is an almost verbatim repeat of x, it shouldn't be that hard to figure out that article x is the original, should it? Especially if they both have time/date stamps....