Coils with aluminum plate behind them?

[RubyCreekTed]

1977 Evinrude 55hp. I just replaced both coils because the motor was running very poorly especially after it warmed up. It would not idle at all. Question. The replacement coils my parts guy sold me had a aluminum plate that the instructions said to install behind each coil. My old coils had no such plate. The pictures in the instructions show the coils in a 3 cylinder motor, mine is a 2 cylinder. I choose not to use these plates as they would have prevented me from removing the spark plugs as a corner of each plate would have been within 1/16 inch of the spark plug center connection where the boot plugs on. Is there any reason I should have trimmed this plate and used it or is it alright to leave these plates off. The only thing I could see they would do is shield the sides of the coil from the engine heat but the center of the coil sets in a hole in the plate so no shielding there.
RubyCreekTed