Did one of these authors get totally ripped off?

I ordered two different books today on Amazon for my kindle. I want to clarify that they are by two different authors. I went to read one of them, and then I decided to read a few chapters from the other one. That's when I realized, "Did I actually switch books? This information is exactly the same, word for word, as the other book." I'm not sure why it was EXACTLY the same, but with the economy and all going the way it is going, I shouldn't have had to pay for two of the same books. When I ordered them, the covers and authors were different, but why then do they have EVERY SINGLE THING ABOUT THEM the same? I'm not so much as worried about the money, because the books weren't that expensive, but one of the authors got totally ripped off, and that isn't fair. I know how hard it is to write books, especially ones packed full of information, and it isn't right that somebody gets to make money off of pretending that they wrote all of it. So, how and where can I get contact information for the Amazon website?