Please see above link where it explains this.

Thanks for the reply, Lowlander. What are the two tags that MM is updating?

MediaMonkey saves the Track# to multiple tags for compatibility, some programs choose to show both tags as a multi-value, instead of choosing one like MediaMonkey. This is not something the user can change in MediaMonkey.

When I edit the track number of .m4a files, MM2024 (2024.2.2.3222)) looks like it's putting a single value in the "Track #" field. However, when I look at the tag via Mp3tag or foobar2000, it's not a single value. For instance, if I set the track number in MM to "1" and edit the tag in Mp3tag, the value is "1\\1". When I edit the tag in foobar2000, the value is "1; 1".

If I edit the "Track #" field on an .mp3 file in MM and view it in the other two programs, the value is simply "1".

I'm exporting my playlists to another program, and this is causing the program to display duplicate track numbers on every .m4a file.