If I define a column containing bot the filename and extension, as in
And I edit the name by changing the extension
01 Some Music.flac
01 Some Music.bak
Mp3tag automatically re-adds the extension again and the file end up being renamed to
01 Some Music.bak.flac
Mp3tag needs to be smarter when the value and field contain the extension, and not add the old extension when renaming the file.