Hidden and conflicting tags in MP3 files

I've recently changed the media player I use from Windows Media Player to MediaMonkey. The transition mostly went well but I have had some nagging tag issues with a few MP3 files. I use MP3Tag as my tag editor but these few files, which looked perfect in MP3Tag were being incorrectly identified by MediaMonkey which showed alternative tag values to those displayed in MP3Tag.

I have have concluded that there must be two sets of embedded tags - is that possible? I note that MP3Tag identifies most of my MP3 files as having both ID3V1 and ID3V2.3 variants embedded. Does this explain the mystery - until now I assumed one was just an extension of the other and that the values of both would be the same.

To help resolve my challenges, does anyone know of a utility that shows both sets of values?

Of course, if I'm off beam here about the cause of my problems, could someone explain what is actually happening and how to deal with it.

BTW - I've had no issues with my FLAC files.

Many thanks for your help.

Mp3Tag reads the tags in the order Ape->ID3v2->ID3v1.
So this might be a possible reason if your tags are not in sync.

Have a look at Tools->Options->Tags->MPEG for your settings in Read and Write.
If you have different content in ID3v2 and ID3v1 you can observe that in enabling and disabling the read-option. I.e. to see only ID3v1-tags just have only this enabled.
Normally Mp3Tag puts ID3v1 and ID3v2 in sync if both are enabled to read and to write and you save the file again.

But there be other reasons. The file can be corrupted, which does not always mean that you cannot play the file or all software shows a problem.
Check your files for errors:

Thank you, poster. With your help I have discovered a whole new world of tag detail I didn't know existed and more importantly a mechanism for sorting out the problem. The MP3 files that caused the issue were not created by me and the originator clearly used different software. Still playing about but I now have the knowledge to resolve everything.