I've seen methods to remove duplicate tags, but I would like an action that does the following:
Compare ARTIST and ALBUMARTIST fields. If their content is the same then delete the ALBUMARTIST tag, but if their content differs then leave both tags in place.
this is the basic expression:
$if($eql(%artist%,%albumartist%),1,0)
BUT: if you delete the ALBUMARTIST you will get problems on most players in respect to grouping albums together.
Also, I would use a filter as this means that only the hits are treated and not every file get evaluated.
And then it is even simpler to remove fields.
So, to get rid of a field:
Format value for ALBUMARTIST
Format value: $if($eql(%artist%,%albumartist%),'',%albumartist%)