Mario & Luigi 3DS - BCH vs PTX

[Fawfulthegreat64]

This has been bothering me for a while because of how random it seems, but in Mario & Luigi: Paper Jam and Superstar Saga + Bowser's Minions, some models can be viewed while others cannot, and they seem to otherwise be the same thing. For example, I can open B_F_underground_06 but not B_F_underground_05. I looked at them in a hex editor and found the most likely reason, so this image better explains it:



I'm wondering if anyone knows more about this and/or knows how to make Example A readable by the programs since it does have the BCH stuff, just a bit further down.