Hey Bob - what about the rule that the start line was an obstruction at all times?
Depends on how it is defined in the sailing instructions.
Two downwind boats coming to the gate. If they round port (downwind left mark) then the Starboard boat has inside room at the mark. If they round starboard (right mark while looking downwind) then port boat has inside rights. Know that they will both be rounding the same mark whichever mark they choose. How much room does each have to give in each of these situations?
Eh ???????
If they are rounding the left mark or the right, it does not matter, they must round "in a seaman like manner".
If they are rounding one mark each, and assuming the marks are far enough apart that 2 boatlengs cannot apply (which you would hope or there would be no point in having both marks) then simple Port vs Starboard applies.