The answer to your two questions are no and yes.

Local management and/or whomever is doing the revenue management for the property (it could be Hilton or it could be done in house via the management company) regularly over-authorize room types and/or the entire hotel. An example being a property has 30 standard king bed rooms, but they will set it up to sell 35 or 40 and then the desk staff day of arrival needs to upgrade or change room types all night long.

If the property has a history of a lot of no-shows, instead of selling the actual number rooms the hotel has (for the example I'll say 150), they'll set it up to sell 153, 155, 160 or whatever assuming there will be no shows. If everyone shows up, that hangs the desk staff out to dry but the people who make these revenue decisions never face any repercussions for their choices from the operational staff that has to figure that part out.

If you're booking some superbly specialized niche room type, then I would assume that it'll be there because no one is deliberately messing around trying to sell 2 of something you only have 1 of, but IME, anything past that is fair game to be manipulated.