Just read the description carefully, or you won’t understand )
Look at the flashing small circles in the center of the larger ones.
They flash differently, don’t they? When one is white, the other is black. Right?
Well, no. Click on "Add/remove surrounds” and watch how they actually flash.
I didn’t believe it at first. I even took a screenshot ...
Anyway, they flash at the same time and have the same color when flashing.