Duplicates on Ipod

I used to have the same problem. This is usually caused by "mismatched ID3 tags". What happens is, you'll have two songs by the same artists, but the tags are different. For example, you might have one tag that says "norah jones" under the artist tag, and another that says "Norah Jones" under the other. Music match is smart enough to put both these songs under the same artist in your music match library, but when it synchs to your ipod, if any nuances exist (such as a capitalization or space error), then the ipod will sort them into two different artists.