Shared music folder is much bigger than it should be

Hi all, after much frustration , I am seeking your advice.  Just bought a MBL weeks ago and since then, it is my second factory reset, as the music folder which should contain no more than 200 G has grown to cover 80% of all the disk space.   I can’t figure out what is going as the folder shows the right amount of music files but in reality, it takes much more space than necessary.   If the files have replicated by themselves, I cannot find a way to access them as the only files I can accesss are the ones that are the valid files (which should take no more than 200G.   I am new at media folders but suspect that MBL is creating multiple copies of the music folder and make them but one unavalable.  I hate the idea of having to start with a clean slate again.   Painfull and long.  Any idea?  

Where are you checking how much free space you have available? Check if you have a backup program that is making a copy of all of the files that you have in you PC to the my book.