I see that my issue was posted on April 18 by MA14urj. However, since it was never answered, I am going to post it again.
With Adobe Reader 9 - all versions - booklet printing worked great. With PC Adobe Reader X, if you try to print more than one copy, they all combine into one stapled copy. (As I type this, I am going back and forth, and printing 21 copies of a 38 page booket ONE AT A TIME).
As MA14urj wrote, "With Adobe Reader 9.4 it was working fine, since Update on 10.0 / 10.0.1 we have the error on 2 or more copys of a document they are stapled togehter, so they are useless!"
Someone please help us! Is there a solution? Is Apple working on this issue?