Alright let me clarify, since you seem to be getting conflicting information and that is confusing. You only need one accurite.
You want to measure the hottest point your snake can reach in the enclosure. Put the probe for the accurite right on the glass where the UTH is under the substrate. Don't use tape to tack it down since snakes are well known for getting themselves stuck to any tape in the enclosure. There is a little sticky pad on the probe, but once you need to clean you can't really use it again. A dab of hot glue is a good option.
The rest of the unit goes inside the enclosure on the cool end (opposite the UTH). The indoor/Humidity measurements will be taken at the unit.
Now the probe that is attached to the thermostat goes OUTSIDE the enclosure, taped directly to the UTH.
Hope this helps!