While in a poker game you don't hand out all cards and the order in which a player gets their cards before a betting round (first two with texas hold'em) also doesn't matter. Takes unite a few arrangements out :)

For scale: that’s about one deck for every atom in our galaxy.

Yes, as long as you give it a true shuffle, as a casino would. Casual lazy shuffling may produce duplicates.

> likely will never again

That's a pessimistic view of the future.