Music Library Issue

On my Desire S I have loads of albums, all organised into folders. For some of the albums, in the list of albums, they are showing up twice. Not duplicated though. Some of the album songs are showing in one and rest in another. The ID tags all show the exact same album name. The only pattern I have found is that the songs were "created/extracted" at different times, and using different programs. But surely this shouldn't matter as the ID3 tags are all showing the same common information.

Is anybody able to help? Many thanks