Also the entire planet would run out of oxygen.
This would not happen for so many reasons.
Would the earth get too heavy and fall?
No. This is not how orbital mechanics work for so many reasons. Also the Earth outweighs humans by a factor of roughly ten trillion, so in this scenario we'd just get an order of magnitude closer. This would affect absolutely nothing.
I'm not sure, but this scenario has been giving me the spookers.
You're afraid that sixty-six billion people will appear out of nowhere in blatant violation of the Law of Conservation of Energy. This will not happen. You should be afraid of things which can actually kill you, like cars, firearms, and nuclear weapons. But sure, let's suppose this happens.
The current global human count is roughly 7.4 billion. This means in your scenario, there are now 74 billion humans. Current estimates say that, if we were to most efficiently utilize farmable land, the Earth can support around 10 billion humans. So clearly food is going to quickly become a problem.
Let's say these humans are generated in a distribution that mirrors the already-existing world population, and let's say they're also given identities so that they can't easily be picked out of a crowd of other humans. What happens next?
Well, there simply isn't enough food for everyone. The entire human race begins, collectively, to starve. While certain areas may take matters into their own hands, this simply wouldn't solve the overall problem. So almost everyone is going to starve to death. Maybe a lucky couple million survive - but they would be in pockets, in isolated areas that are difficult to get to. There probably wouldn't be any groups with enough genetic diversity to survive in the long-term. So, ultimately, humanity dies.
Let's say that the government comes to this conclusion, and decides to do what others have already suggested and commit mass-genocide. Well, unfortunately for us, the way I've set up this scenario states by definition that the new humans aren't easily picked out of a crowd. So we can't just kill all the new humans. So if the world's governments did collectively decide to pare down the human count to 7.4 billion, there's a 90% chance that any individual person gets chosen, regardless of whether they're a generated or pre-existing human. So humanity as a whole would survive, but you will probably die anyway.
Regardless of what happens, it's very likely that you die, even if humanity as a whole survives.
