Library picking up content in another source

[BruceCPippin 1]

I created an "Audio Books" library.  The Author\Books appear as expected after pointing it to a folder called "Audio Books".  Unfortunately, it is also including content that is definitely not in the "Audio Books" folder.  It is picking up content from a "Music" folder which was not included when setting up the library.  It's not a great deal of music but I have no explanation for this behavior.  Can anyone provide an explanation?