Originally Posted by
InkUnderNails
Two quickly answered questions:
Are the machines calibrated or checked with a "known contaminant" test strip?
If yes, is it possible that this was what the OP saw tested as their sample?
Now one that is not so easy:
Why would they do this?
Yes, several times a shift. Is it possible? Sure it could happen, however unlikely given that the calibration strips are kept no where near the units and are only pulled out when a calibration is being done. And as TSORon pointed out, they look distinctly different to avoid putting in the wrong strip.