Trane twin centrifugal chillers

[Cajunmech]

I am researching Trane twin centrifugal chiller performance and I have a question that may seem to be fully explained in the Trane literature but here goes. The literature states that there is a common evaporator and a common condenser. It also states that each compressor has the ability to spray liquid refrigerant along the entire length of the evaporator tubes. With a common evap and condenser does this only pertain tot he water side of these vessels? Do these chillers have a separate refrigeration circuit? If so how can one single compressor spray liquid refrigerant over the entire length of the evaporator tubes?

Can someone give me some clarification on this?