Radiators.....Single pass or Dual Pass, which is better?

I figure dual pass radiators are better because or the retention time. Any thoughts?

What is a dual pass radiator? Does the coolant circulate in the radiator twice before returning to the engine?

you can tell dual pass rad's . in/out on same side. said to cool better

I haven't seen ANY difference.
With a Dual-Pass radiator you have half the volume, twice. So, the amount of time which the coolant will spend inside the radiator is exactly the same. The Single-Pass radiator will slow the coolant transfer to half the speed of the Dual-Pass where the Dual-Pass will have the same area but, the coolant will move through half of it, twice as fast.
The amount of heat transfer time from inlet to outlet and radiator cooling area which the coolant will see is EXACTLY the same.

can't see were it would have twice the area, same coolant volume . if it did have 2x area speed would be the same . far as i know , volume of coolant and air flow is more important to coolant speed . Add: area is frontal not type of tubes or fins , those being equal