False. I almost never upvote an article without reading it, and half of those upvotes are because I already read something similar recently that gave me the same information.
I'll submit in the second case (already read something similar) that, properly speaking, we should read both, and upvote (or submit, if not already here) the better of the articles.
Not that, you know, I often take the time to do that, either - but it would improve the site and the discussions if we all did.