If there is still unsealed larvae, that means the queen must have still been laying eggs after the queen cell your new queen came from got started.
So there are 2 scenarios, one that it's a supersedure or two, the bees made a new queen so they can swarm.
Supersedure is less likely in your scenario, swarming is much more likely. Could be that all that feeding stimulated them to swarm, they may have swarmed already, the old queen leaves with the swarm and the new queen takes over the hive.
You can tell though, if the old queen is still there, there will be young unsealed larvae, and eggs.
So there are 2 scenarios, one that it's a supersedure or two, the bees made a new queen so they can swarm.
Supersedure is less likely in your scenario, swarming is much more likely. Could be that all that feeding stimulated them to swarm, they may have swarmed already, the old queen leaves with the swarm and the new queen takes over the hive.
You can tell though, if the old queen is still there, there will be young unsealed larvae, and eggs.