Try to keep the chicks all together in one space if you need to employ two heating pad caves. Chicks need to be part of one single unit or you may see conflicts later on.
I was using a mercury thermometer to test my MHP cave this past week just prior to bringing home my chicks. When I laid the thermometer inside the cave as it was sitting on my work bench in the garage, it registered over 100F at the #6 setting. It was warm in the garage, maybe 70F or more.
Then I took the set up out to the run and turned it on to #6 and measured it. It was 85F under the cave and the ambient temp was in the low 60s. Also the ground temp was much cooler than my workbench. So all of these influence the reading you'll get inside the cave.
Yet in spite of the reading, the pad will stay the same temp as chicks contact it with their backs, probably in the high 90s at the highest setting. My new chicks have been doing splendidly in spite of the night time temps getting down in the high 30s. They are just three days old today.
By the way, I gave them meal worms yesterday, and OMG, what a hilarious show! The first one to grab a worm took off running and cheeping madly, doing the quick twirl and reverse, and the others just stood there watching this spectacle, wondering what had suddenly caused their brooder mate to go nuts. When the others caught on, it was chick pandemonium!
They've been getting grit for two days now, so figured it shouldn't be wasted.