There's only one entry for the album in the database. The entry can, however, be displayed in several folders at the same time. For example, if you have an album by Simon and Garfunkel you may see it twice, under Paul Simon AND Art Garfunkel.

So, in order to fix the problem, simply double-click the entry and make sure only one artist is listed in the album.

Alternatively, select "Artist - no compilations" from the drop-down box on top of the content tree. This mode will ensure each album only displayed once.

I hope this helps.

Andrei