In order to answer your question as to whether or not the number of duplicate stamps is above normal, one would have to look at the wording of the original ad.
Assuming you're referring to the "Forever" Liberty Bell Stamps, there are a remarkable number of subtle varieties one can collect in this series. Here's a link that can help you identify the various ones. It's a sub-collection all in itself and some collectors would be grateful to have such a quantity of Liberty Bell stamps to go through in order to search out some of these varieties:
http://www.sandiegophilateliclibrar...er-stamp.pdf