Read what is described in the messages above in this thread. You do not need any Mp3tag action, just some manipulation of the Mp3tag options how to read write Mpeg ID3 tags.
Yes, it is possible. Copy a ID3v1 tag field with a different field name to the ID3v2 tag, so that you can see the content of both fields when viewing ID3v2 tag.
If it is not there already, then insert a new column into your list view.
Name: TagRead (TagTypes)
value: %_TAG_READ%[ (%_TAG%)]
Having this column you can easily see what tag types exist and what tag type is currently read.
Use the dialog "Mp3tag/Options/Mpeg".
Set
Read ID3v1 only
Write ID3v2 only
Close dialog.
Refresh the view by pressing [F5] or use the menu "Mp3tag/View/Refresh" instead.
You should now see only ID3v1 tag fields.
Run an action "Format value".
Field: ARTIST_ID3v1
Formatstring: %ARTIST%
This is an example just for one ID3v1 tag field ARTIST.
You have to do this for the other fields too, if you need them.
Note: You cannot see the result after running this action, because you currently look into the ID3v1 tag, although the tag field ARTIST_ID3v1 has been written into the ID3v2 tag by the "Format value" action.
Use the dialog "Mp3tag/Options/Mpeg".
Set
Read ID3v2 only
Write ID3v2 only
Close dialog.
Refresh the view by pressing [F5] or use the menu "Mp3tag/View/Refresh" instead.
You should now see only ID3v2 tag fields.
Use dialog "Mp3tag/View/Extended View" and see both tag fields ARTIST and ARTIST_ID3v1.
If you want to see both tag fields in the list view, then insert a new column:
Name: Artist ID3v1
Value: %ARTIST_ID3v1%
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