Easy to fix, you just need to remove that empty texture slot between your normal map and ao map, so just press that little up arrow at the right side of texture list when ao texture(texture.012) is selected.
I recommend to name your texture to reference what is your texture supposed to be. for ex.
texture.004 -> MarbleD
texture.011 -> MarbleAO
and so on… if your scene gets much bigger and you add more textures, that kind of naming will help you at the end alot.
Edit. Actually it did not work, looks like the first ao texture gets messed up if the second looks correct. Definitely a bug, works great in GLSL view but not in game. I recommend doing that same setup with material nodes.
I’m fairly confident it will work. If you need help with nodes, just ask.