Comment by dan-robertson

0.90005 times 10 is 9.0005, not 0.9005 (I.e. the two fractions presented are 90.005% and 90.05%). Even if you look at the complement you get 9.995% vs 9.95% which is small. One could imagine that these differences could also arise from eg obstructions to airflow or positioning in the room or the direction of the wind outside. The point is that the difference is dominated by air flow in a typical environment rather than filtering differences.