Folks,
I definitely won't map both tag fields to TPE2. This would introduce further confusion and I don't feel like investing my free development time for hack-fixes and workarounds that would be needed after introducing a mapping of two field names to the same ID3v2 frame.
I've mainly changed the field mapping due to constant moaning of some users who were not satisfied by the cognitive distance between the description BAND and its intention to serve as the field for album artist.
After the discussion in this topic I got a feeling of what I can expect for the final version regarding user feedback and think that I'll revert this change.
Florian