3000gt style dual exhaust: One down pipe one Cat, whish splits into two pipes that go back to the mufflers
True dual: 2 sets of cats and pipes one from each "Bank" of cylinders.
I.E. one pipe for the front 3 cylinders, one pipe for the back 3 cylinders (usu it would be one for left, one for right, but because of the engine placement, i said F&B)