Every time you add a music track to your iTunes library, a copy of the file will be created automatically in the iTunes folder (in C:\Users\Username\Music\iTunes). If you are tired of iTunes copying your music files upon importing new audio CDs or MP3 songs, here is a quick way to turn this feature off.
How To Stop iTunes from Copying Music Files
Open iTunes and click on Edit > Preferences. Go to the Advanced tab and clear the checkbox that reads Copy files to iTunes Media folder when adding to library: