So every time I pick an album to play I get three of the same song, so how can I just play the songs once?
Unfortunately - you have let Media Center impose it's will over your music locations and now it's displaying media in it's library from three different areas/drives.
You need to decide where the "master" stash will be and have Media Center ONLY look there for your tunes. Or continue to use three locations - if that's your thing - but ensure that all duplicates are removed from said locations.
To fix - Go to Tools->Import-Configure Auto Import option. You will most likely see your three locations listed. Decide which folder locations to keep and clip the others away.
Then - dependent on the duplicate overrun you currently see in your library - if it were me - once I have reset my main media path - I would probably clear the library and then "re-import" the media from the new single location.
To clear the library - use File->Library-Clear Library.
WARNING - this will wipe all media references from the current library. It will not touch/delete/alter your actual media files. Be sure this is what you want to do.
Then - once the library is clear and the media path is set...
Go to Tools-Import-Run Auto Import Now.
This should refill your library with just a single instance of each track - all coming from your main media location.
Let us know how it goes - or - if you are unsure about anything - ask away
VP