every time I add a new song/album to my IPOD touch, it will start syncing music I already have

When adding a new song/album to my IPOD touch 4th gen., After adding the new songs, it starts adding music (copying) I already have on my IPOd. I have to cancel by clicking the (x) every time after my new songs have been transferred. I have the autofill off, and am managing my music manually. This started happening after updating to the new ios. Any help will be greatly appreciated