Fix for Issue #146 per my discussion with avanderhoorn

Ironically, I was not able to immediately reproduce a scenario where multiple instances of the IAuthorizationFilter are returned in the sample project.  However, I was able to test the change against my original project and it started working.  
PS: this is my first pull request. I'd welcome any guidance if I messed something up, like i.e. is the merge operation from my local fixes branch need to propagate all the way to my forked repo?