the two are joind in the frame. the bottom 1 is softer so as you land that takes about 75% of the landing (depending how hard it is) then the top one takes any large force as it is alot harder then botton shock and is better than nothing.
Where the first shock pivots ,where you can't see it under the frame , they are actually attached . The Guy , Karpiel,was an Air craft landing gear engineer ,who holds several patents. The deal is the two link braces holding the Frame together are way shorter than a FSR linkage ,which makes it's stronger . It's called parallel linkage . This design was the predicessor to the DW link . So the new disco must pedal like a muther , because the shock is near the BB ,giving it minimal pedal bob .