If user has decided to only embed front cover art, e.g. by setting the Options / Cover Art / Only embed a front image, but the cover art found has both e.g. front and back "tags" associated with it, then these are embedded in the MP3 file with both front and back "tags" and apparently (see http://forums.musicbrainz.org/viewtopic.php?pid=24288) some players have an issue with multi-value cover art "tags".

The proposal is that if the "Only embed a front image" has been checked, then any embedded cover art has any "tags" or "types" other than "front" removed.