Never refer to the same JAR using Class-Path from two different modules. (It will get loaded twice and could cause strange problems.) If you think you need to, generally this just means you have not factored out your module dependencies thoroughly: split off a third module to hold the library.
A. Cal\`ı, G. Gottlob, and T. Lukasiewicz. Proceedings of the 12th International Conference on Database Theory, page 14--30. New York, NY, USA, ACM, (2009)