Hi Cybershyguy.
This is what's happening: On my computer: If I put 5 folders under "music", under "libaries" and some of these folders have the same song in them, WMP picks up all of the songs in ALL the folders and puts them in its library, thus reflecting duplicates in WMP library. Stay with me..............If I move four of the folders out of the "music" catagory and put them under "documents", under "libraries" on my computer and leave just one folder under the "music" catagory, WMP only reflects the songs in that folder in its library.....thus no duplicates. The problem is: what if I wanted to put other songs outside of the one folder into wmp........I would have to open another folder with those songs excluding the ones already in the one folder. Did you get this???
To summarize: WMP picks up ALL songs in ALL folders that are in the "music" catagory on the computer. If there are duplicate songs in these folders, it causes duplicates on WMP side.