Yeah, Use media monkey to do this, Select all the Tracks, give them 1 album name, set the artist to various artists you can leave the track name etc and clear all the rest. You then delete all known artwork for those tracks, Set the new artwork to all selected items insert into tag and voila.
i used to use mp3tag , i cant remember why i went to media monkey but it did something better the mp3 tag , havent tagged songs for ages both good though
You changed to Media Monkey due to the renaming facilities and the ability to create folder structure and file naming any way you want it. Along with easily assigning just the 1 artwork for everything.