I guess that behavior is correct, because you are deploying singleton  class in different modules. Unless you follow a pattern  like

java.sun.com/.../ServiceLocator.html

This is completely dependent on how you deploy  it and how you manage the clustering, but the class  itself is still a singleton. In an framework environment such as J2EE containers, you need to look at ways of deployment as well as the pattern you are following.

Yet, I would like to get others opinions too.