A:Answer Why would you want 2.
Unless you are setting up a complete system in a room far away from the primary, you wouldn't need one. If you are setting up a second system, that is further away, it would make sense. And you can set up several areas. As a matter of fact, i have a arc, and sub, and 2 One SL's in my living room. It required that i set up two zones and then combine them . The operational aspects of Sonos, can be totally confusing at first. But it just takes some patience with trial and error, to get the best sound I've ever had. Sonos is unbelievable.
I have a MOVE that's on a separate zone. It can be combined with the other two easily ,if your moving outside, or somewhere further away from the main system 'ARC" , Playbar, ect,