But, if you use multiple meters, you'll need a minimum of three identical meters. If you have two, and they disagree, you have no way of knowing which is wrong. Since the odds are strongly against two meters drifting out in the same direction the same amount, three meters means when two agree and one does not, the odd one gets recalibrated.
Originally Posted by DREW WILEY
I presume that by "several" you mean "more than two".