Having both [B]MP3[/B] - IDv1, IDv2 tags could conceivable create incorrect display problems with some playing devices. I would recommend only having one.
I will give you an example, My Alpine unit will display the tags incorrectly if I choose to have both tags filled in and active. If I choose just one then everything is displayed correctly.
Make sure that you know which version is supported. Stick with just one.