JKDOS
Senior Member
Hmm thats strange. The only time I can ever think of needing 2 copies of ACNH is if you're doing a island transfer or playing local co-op using the airport.
Using 1 copy and Primary/Secondary setup means the game can only be played on one Switch at a time, and the secondary must be online at all times in orders play. It's possible the DLC for HHP will have the same restraints, but since it's DLC and not a game, I'm leaning towards it being possible that it will just work without internet requirement, and work at the same time as it being on the primary Switch, though it's not important to me that it work at the same time since it has no multiplayer