The point is that before leaping into second shooters scenario’s that can avoid detection from cameras in the casino, who leave no forensic evidence behind and a conspiracy by local police and hotel employees to hide the evidence of two shooters that there may be reasons more simply explained.
A possible second theory that I have is air flow. With two windows open he could reduce the smoke in the room.
There are any number of simple reasons that avoid the necessity of two shooters.
A good theory. However, if that was the reason, it would make much more sense and be far more efficient to break another window, in the same room and not the room over where a wall (w or w/o a door) is in the way.
I don't believe there were two shooters. If investigators had any reason to actually believe that, there would probably be a nationwide manhunt by now.
I'm only speculating that Paddock may have expected to have someone else there, but that person never followed through.
The smoke clearing idea makes sense, but these windows were broken in two separate rooms, with only one doorway separating them. If that were my reasoning, I would have broken a window on the opposite side of the same room, not along the same side of the building in a separate room.
Airflow is a good reason. Making it look like there is more than one person would be another. It wouldn’t be the first time in history someone used the tactic of making it appear that their forces were bigger than they actually are.