Adding a Folder to Your Library
One of the easiest ways to copy a music folder to iTunes without duplicates is by adding the folder to your library. Every time you manually copy a folder, duplicates are created. Once the folder is added to your library, iTunes will add any new files you place in the folder automatically without creating duplicates. You only need to add the folder to iTunes once. This process should be completed before any duplicates exist on your system.
By default, the iTunes folder is located in the following directories, depending on your OS:
Windows Vista or 7: \Users\username\My Music\
Move the contents of the entire music folder to the directory above. Change any download settings to automatically place new files in the new directory. iTunes will automatically import newly added songs without needing to copy your music folder each time.
Adding a Folder Through iTunes
If you know that copying your music folder will create duplicates, you must import the folder using iTunes. This adds the folder to your iTunes library. You can add one large folder or individual folders, such as a single album or artist folder.
Open iTunes. Go to File. Select Add Folder to Library. Choose the folder you want to add to your library. This works best if you add individual folders versus your main music folder. Press Open to add the folder without causing duplicates.
If you do not want to add a folder to iTunes each time you add music to your computer, you can change the iTunes settings to automatically import your music without causing duplicates. This setting prevents iTunes from creating a copy of your files each time you import. Instead of your files being store in the iTunes folder, they are stored in their original locations, resulting in no duplicates.
Open iTunes. Select iTunes if using a Mac or Edit if you're using a PC. Select Preferences. Select the Advanced tab. Uncheck the Copy files to iTunes Media folder when adding to library. Press OK to save your changes.
The best way to prevent duplicates is to store all your music in the iTunes media folder by default. If you download from sites other than iTunes, choose the iTunes folder as your default download folder.
By utilizing some of the methods above, you can manage your iTunes collection without having to deal with duplicate songs. Duplicates take up space and can make finding the right song harder. Not to mention, it creates a larger library than necessary. Start by removing all duplicates that currently exist and then take steps to prevent duplicates in the future.