The cddbid tag has to be inside volume clause:

Code:
<!--[album(all,artist,title)]--> 
 
<!--[volume]--> 
<!--[if(cover)]--><!--[cddbid/]-->.jpeg<!--[/if]--> 
 <!--[/volume]-->

<!--[/album]-->
That means, covers will be displayed separately for each item of multiple-item-sets.

Regards
Andrei