Hexadecimal code doesn't match with Invoke Battle?

I'm trying to have a specific monster appear when you kick the treasure chest in the imperial camp.
Event CB/0DFB tells me it invokes a battle with a certain enemy formation. I took the formation with the desired enemy, turned it to hexadecimal and replaced in CB/0DFB 4D 2A 02 with formation nº 43, to CB/0DFB 4D 2B 02 but instead of getting me formation 43, it gives me formation 67.

So I checked what formation 2A gives me and it turns out it's 66, not 42 which would be the decimal translation. I tried searching for 2A - 12 (hexadecimal), 14, and I get another different formation! What's going on here?