freejung - 9:00 pm on Jun 30, 2011 (gmt 0)
Adding a sentence or two is one way to do this; even better would be to make it completely unique
Google's public spokespeople tend to word things very carefully, and you have to exercise fine reading comprehension skills to understand what they mean.
In this case, JohnMu is not telling the webmaster that having more content would help. He is saying that having unique content might help. One way to achieve unique content is to add more words to the duplicate content you already have. Another way is to remove the duplicate content and replace it with something unique. Just going off of what was said in the comment, it is entirely possible that the replacement text could actually be shorter than the original and nonetheless rank better because it is unique.
It's important not to read things in to these kind of statements that they are not in fact saying. Also, of course, keep in mind that the statements may not be accurate, but even if they are accurate, that only works if you understand what the statement actually means.