As a brand new Dot (6-pack) owner, colour me impressed.
I was unaware that the 2nd Generation Dots came with Echo Spatial Perception, and what it meant. Before receiving my devices, I had been reading articles written about previous versions that dealt with multiple devices in adjacent rooms, and I assumed I would have to configure some to "Echo", and some to "Alexa".
But to my delight, no. I now have one in my home office (small bedroom), and one in my bedroom at the back of the house. With either one switched off, I can activate the one in the other room, so they can obviously hear me throughout. But with both switched on, only the closest reacts to my commands. No clash, no problem.
This bodes well, as I wanted to have one in my lounge, connected to the stereo for entertainment, and one in the kitchen for shopping/recipes/timers/etc. - again, i thought they might clash, but now I think I will be fine.
My understanding is that Echo Spatial Perception will be rolled out to earlier devices as well, which doesn't affect me, but is good for those who have the older Echo and Dots.