Welcome to Beemaster,
The bees could be drifting from the weak hive to the other hive making it look like it is booming.
Are the hives sitting next to each other?
When you did your combine, did you find the queen in the weak hive and pinch her?
How did you do your combine, newspaper?
The brood you saw in the weak hive, was it worker or drone?
Are things still blooming good in your area?