I've noticed this before, and I'm sure many of you have, too: you can often take creationist comments, especially when they're lengthy, run them through a google search, and discover that the were lifted wholly from some other source. If you read the creationist literature for any length of time, it really begins to sound all alike, because what they'll often do is cobble together their treatises by lifting whole paragraphs and pages from previous creationist tracts. It's the kind of thing where, if they did it as a student in my class, they'd get an automatic fail, especially since they rarely bother to include attributions.
Here's another similar case: Hamza Tzortzis, the Muslim creationist, wrote a critique of Dawkins' The God Delusion. Guess what? It's a copy-pasted pastiche of an article by William Lane Craig. The original Craig review was pretty bad, but running it through a copier a few times just makes it worse.
The Immortality of technical prose is a long-known about phenomenon - I think Stan Kellly-Bootle was the first to actually call it that. (A fun game is to try and identify it after it's been translated into another language and then back into English!) It's hardly a surprise that other areas of non-fiction writing (by which I mean, not intended by the author as fiction) suffer from the same curse.
If it's the case that science writing doesn't suffer from this problem, then the interesting thing would be to look for an explanation: perhaps fear that your paper is going to be reviewed by the very person you nicked from, for example? But I'd be happy to wager that it happens in science writing too.
Many thanks for featuring this. More traffic than I normally get in a month! Hamza's changed his article. I've written a followup piece here: http://geoffsshorts.blogspot.ie/2012/06/interfaith-dialogue-revisited-hamza.html
Perhaps if they change a little bit every time they are copied, over millions of years they might evolve into something that makes sense.