Featured image appears twice (full width and normal)

I'm trying to use a full width header image for certain pages - a different image for each page. I've chosen the option to use the featured image, but this image shows up both full-width and, right below it, in its normal size in its normal position. How can I have a full-width header image and not show the regular width featured image? Also, is there any way to show more than one full-width image on a page? I'm not talking about a slideshow, but rather one image appearing below another. See, for instance this page.