Comment tag vs. Comments field in Windows

[ohrenkino]

see here for the basic problem:

[X] Setting comment field

Sounds like the problem with the language descriptor. Win Explorer only displays comments with the same language as your Windows system. Read /t/11025/1 and set _M_STR_ID3V2LANG to whatever language code your Windows is using.

It's probably a problem of the language descriptor. if that does not match, you probably get 2 comment fields.
It would be easiest to run these files through mp3val and repair them.