orifice plates are one of the most simple and widely used instruments for measuring discharge. The reason behind this is the simplicity and less expensive setup cost of the system. They are good where you need an approximate value of discharge. Apart from these advantages they bring them the disadvantage of inaccuracy and creates losses in the system which an instrument should not. The orifice plates are highly prone to scale deposits at orifice and creates turbulence at head measuring areas near wall taps.

so, in my view using a system with more than one orifice plate will add to inaccuracies in measurement leading to lessening of reliance of these systems.