Yes, exactly.
I think this is what MB wants.
Legit several fronts and backs is different views of the same thing with and without the optional stuff.
Examples of legit several fronts:
- Release “Tina Live” by Tina Turner - Cover art - MusicBrainz
- Release “Phantom of the Paradise: Original Soundtrack Recording” by Paul Williams - Cover art - MusicBrainz
Examples of legit several back:
I don’t agree, there, this contradicts your definition above.
Boxsets should not have front images for things inside.
In this box for example, you see the usual booklet (set as Poster, here) has no Front tag, because it is inside.
Example of bad muti-fronts and multi-backs:
Only the first front and the first back are correct.