two faces of the same model

[itmemario]

I downloaded the zelda breath of the wild model and the model made me confused by having two faces (one with a diffuse texture and the other one with ao map).
So i wonder what use did the other face have for them to include a duplicate with the same faces count ?

[Koopa512]

2 uvmaps, just create another uvmap on one and copy the uvmap on the other to that new uvmap