What I think happens is that it’s because if you used gasoline to kill Risadinha before going to Alexandre’s trailer to disable the gate locks, the game saves Risadinha as dead, and when it saves the locker guy before that, it also saves him as rescued. Unfortunately, it ended up like this so it wouldn’t break the continuity between acts if the player dies after opening the gates on the PC. If you did it in that order, you’d have to start a new game to get Ending 1.
To get Ending 1, neither of these two things can be done.