How confident are you in the accuracy of your thermometer?
I ask because there is a chance that your Stages temp measurement could be the “right” one. Just like checking power data, you really need either an officially calibrated data source, or a few devices to see which correlate or differ.
Stating that, I suspect your thermometer is probably irrelevant. Presumably the Stages is calibrated at the factory (note: a true Calibration and not the Zero Offset that you perform… because they are very different) and that calibration uses the Stages temp device. As long as that device is consistent and operating like it did at the factory, you are probably good to go. The potential fact that it may differ from your other temp device may well not matter at all.