That's because second gate's code doesn't contain any of the first gate's images, it has it's own ones and you have to look around for them, sometimes solving other puzzles or finding levers/buttons so you could get to them.
I did and I cant seem to get it to work and of Couse the walkthrough ant much help EDIT figured it out for some DUMBASS reason the guide had the right anser marked as a decoy
