If you install, uninstall, or re-install a program when you are connected to different networks, several instances of that program can appear on the Exceptions tab. This is because if each network that you connect to has a different network location, you must create an exception for each category. For example, you might create an exception while you are connected to a "Public place" network, and then, later, you might connect to a "Home or work" network and create that exception again.
This can also happen when Group Policy is applied.
