Don't feel too bad. My first year I had one hive, and had 100% loss. Second year I ran 10 hives and had 10% loss.
Ditto of frame reuse if no FB.
Did both hives die? Was a queen present in the dead cluster? Can you tell us a little more about the larvae that were present? (e.g. capped, not capped, stage of development, sunken cappings, 'ropy' larvae, moisture in the hive, bee poo in/on the hive, location of the cluster in relation to food source, amount of dead bees both inside and outside the hive, etc. as other will have better questions...)
(Sorry, that got a little more involved than I originally planned.)