the double-slims would throw off the set!! imagine movies 1-5 in double alphas, and then a skinny 6 on the shelf. does that means the cover sheet is adjusted at the printer for the thinner case, or do they simply chop off the edges of the original size?

I don't think anyone here has reported seeing a slimmer case anywhere. As Space_Monkey pointed out, the Scanavo case is a double-wide case. The single-hinged case that I saw at Borders is the exact same width as a double Alpha.