My comment is similar to Moon Yun's in that I'm referring to our first test quite a bit. Mostly because when I make a correction to the test, I immediately realize that I'm making the same marks and corrections that the first test had. I know my subconscious is at work here, because when I come across a sentence, I know from the previous test what word might improve the over-all flow. More often than not it's the same word, or the same striking of multiple words.
Personally, I have a huge fear about accidental/unintentional plagiarism. I think that's why I have such a strong interest in copyediting in the first place. It's very hard to plagiarize sentence corrections, fixes to grammar, and spelling suggestions. However at this point in time I am panicking just a little because I realize it may be possible to plagiarize copyediting marks too!