We are using resp. manufacturing a certain device which measures, among others, the humidity of liquids. I got asked by a colleague if it makes sense to use two sensors instead of one (which a competitor is apparently doing). Mainly, in a statistical manner.
My ideas are: Redundancy: In a technical manner, just a backup. Or to use the one that provides more meaningful measurements (but I guess this is not possible because how can you know which is (more) true?).
Statistically: Using the mean of both. Maybe even with a sensor-specified weight (though I wouldn't). One could define a kind of deviation band in which the sensors must be within. In case their signals differ too much, one knows that something is going on.
Are there some facts which become improved by going from one sensor to two? I'd say, e.g., the confidence is increasing but I don't know how to underline this (statistically). Finally, I'd simply say: The more, the better. Unfortunately, this isn't solid argument.