I placed an order on Sept. 24, 2008 for 2 DVDs and 2 books. I received a confirmation for 4 orders but I didn't check the body of each e-mail, only the subject line. Today I received in the mail 2 of the same DVDs from the same company. In speaking with an Amazon.com representative, they said I clicked the "One click" order button twice. Now, I kow it might be possible to do it once, but not twice! And it would have been by accident, anyway. So, I have 2 sets of DVDs ordered - one already here and one enroute. I may be able to cancel one if it hasn't been sent yet but the one I received, I have to absorb the shipping/handling fee if I return it.
My advice for anyone using the Amazon.com "One Click" order button, check the status of the order within 90 minutes and make sure there isn't a duplicate - if there is, you can cancel it. Also, check the body of your e-mail for confirmation of each order and specific titles. Especially when you are ordering more than one.