I tend to tag my MP3 and FLAC files with front and back cover art. When I embed both, different Windows programs and Android apps will display either front or back as the main/front cover when playing the file.
I have tried embedding them in order of front to back (saving the tag after each step) and of course I am setting the cover type as "Front Cover" and "Back Cover" within the tag.
It doesn't seem to be an ID3 limitation only, because FLAC uses the Vorbis tag system and players have the same problem choosing the order.
Now, the really interesting thing is that even the same player will take two different files from different albums (not within the same file/album), and choose whether to display the front or back cover seemingly at random! As mentioned before, different players are also choosing different covers for the same album.
I can't seem to figure out if it's a tag, player, or tag writing limitation, or something else.
Thank you in advance for thoughts and solutions!