Okay, I'm tired of hearing two broken windows at the Mandalay Bay hotel translates to two shooters.
Makes no sense to have a second shooter in close proximity to the first, it undoes any advantage a second shooter would give attacker(s).
Some people are prone to conspiracy theories when events stretch beyond their normalcy bias.
But there have been many mass murders in the past, even in recent years, where the death tolls have been even larger, and inflicted by a single perpetrator. I assess knee-jerk conspiracy theories in the case like this:
People, when confronted with the reality they're more vulnerable that they imagine, try to overly complicate acts of evil to make it seem they're less vulnerable than reality shows. I suppose it's more natural to acknowledge being at risk if you think there's a bunch of people out to get you. Things get scarier when you see one guy can carry out a massively evil act on his own without tipping his hand prior.