Editors and Lobbyists Wage High-Tech War Over Letters. The net has made it easy to find pre-written letters stating something you believe. Many publications, however, don't think such letters should be printed; since they aren't actually written by the sender (a fair point for a newspaper's Letters page). The people setting up the letters are getting smarter, though. Mix and match terms and paragraphs are just one of the ways they've figured out to vary the message enough to get past editors and into print.
I suspect the papers may have to cave into these eventually; perhaps reproducing a single copy of the message, noting that it was received several times. It's still a valid message; since the people who sign and send a prewritten letter often agree very strongly. In short, it's their point of view expressed in a prewritten letter. It may even be expressed in a far more eloquent and properly-researched manner than the sender has time to prepare. The downside is that you can't tell if it was just someone coerced into sending a copy; or if they didn't read it properly and maybe don't agree with some or even all of the letter's content.