I have two 400A panel boards with 400A main breakers that I am feeding from an 800A breaker using parrallel 600 MCM copper conductors. The panelboards are side by side and the conductors meet the requirements of 310-4. My question is, can I terminate one set of conductors on each 400A breaker or must I join them together in a gutter and run taps to each panelboard?