Quoted from EdisonArcade:
Forgive me if this is a dumb question, but here goes:
I have 2 Switch systems and 1 physical copy of Zelda BTW. In order to both play at the same time, I'll need to purchase another copy.
All of the other games I've purchased were digital, and can play separate games on both at same time.
Game saves are on the system, not the cartridge. You can use the physical Zelda on multiple systems, and each will have their own saves.
You can even use it on a single system and have multiple saves for different user accounts.
You can’t actually play literally at the same time, if that’s what you meant. You’d need 2 carts for that.