Why does my Ipod list an album twice? It's in alphabetical, but then appears near the end of the coverflow as if it was a compliation (but it's not!) ?

I have only one folder in my iMusic folder, so iTunes shows the album once. However, on my iPod (after sync) the album appears twice. In alphabetical order – as it should; but also it appears again near the end of the coverflow as if it’s a compilation album (but it’s not). Both play fine, but why is it doing this? How do I fix? Thanks.