Why are there usually at least two categories (items) on any given DVD on Half.com? Sometimes its easy to tell, like one is the DD version and one is DTS. But then even in that case, sometimes there might be 3 or more categories. Take this for example. One says surround sound and one says digital sound. But, as far as I know there was only one soundtrack version of The Godfather Collection. Also, they have different UPC codes. Whats up?