Even 2 cars of the same color from factory are not exactly matching. Specially with Silver colors there is a slight variation. If you replace one door of both factory paint cars they will differ slightly giving a different shade.
Moreover with passage of time and car gotten old the UV rays and environmental effects create a difference than the coded fresh paint.
So solution for touch ups etc: A good painter will never straight away apply the coded paint to a car. Instead the proper way is to manually match the paint with the car with eye judgement. Let the paint shop or the painter do it for you. And its better to compound and expose fresh finish at some portion for matching the new one so later when you compound and polish the entire car it matches.
My feedback on Civic 2016: http://www.pakwheels.com/forums/showthread.php?t=278004