It’s not hallucinating. Drugs of a certain type will do that, but even then you can still visualize at the same time. It’s a different “set of eyeballs”. A third eye.. if you will.

I don’t know if you know how to lucid dream but I find I can visualize inside one while still just seeing the regular scene in front of me. Even “over there” it’s a separate sense.

There is no “really” seeing. There is just “seeing with this sense”, “seeing with that sense”. You can feel with your right and left hand separately, no? It’s not “one thing”.