I recently had an epic failure when I tried making Sicilian Style pizza.
Join the club.....welcome to disasterville!
Won't be the last time.
You mentioned you let the dough rise for 2 hours and it rose "substantially".
During the two hours was the dough left on your kitchen counter? If so, about what temperature was it inside of the kitchen.....was it warm?
What do you mean by "substantially"? Would you guess that the dough doubled in volume?
After you punched down the dough and stretched it into the pan, how long was it left in the pan before baking?
If you baked it immediately after stretching, did you potentially stretch the dough in a rough manner and degass much of the built-up CO2 within the dough?
What was the temperature within the oven when you baked the sicilian? How long did the pizza stone pre-heat at that temperature for?
What type of pan are you using? Is it aluminim, steel, some other metal? What color is it?
It is difficult to say what went wrong without some more information.
Assuming you used a typical 0.75 oz pack of Active Dried Yeast (ADY), those two packs would equate to roughly 11.75% of the formula flour. That's a lot of ADY in a formula, but not entirely sure that is the sole issue.
As far as the pizza stone, I highly recommend placing your Sicilian pan on top of that when baking. I get better spring cooking on a stone. -k