A few weeks ago during a bee course we noticed a hive that appeared to be preparing to supercede their queen. Supercedure is where the hive decides the current queen is failing and gets ready to replace her with a brand new one. Usually a swarm is not produced.
The hive was apparently healthy, we could see no evidence of the queen failing and there was a good brood pattern. All seemed just fine to my eye so it was decided to re-queen the hive once the supercedure had happened.
The new queen arrived in the post, the hive was opened and the queen search began. There was evidence of a few queen cells that had been torn down and the supercedure cell was hatched… but hang on… the queen was marked so she must have been the old queen. A good laying pattern could be seen with lots of eggs but not a lot of capped brood. On a hunch the search continued and sure enough a second queen was located. She was a bit small and either a virgin or just mated. Both queens were dispatched and the new queen introduced in a cage.
So it is possible to have a hive with two queens. Who knows how long this would have continued before the old one was killed by the hive or the new queen… those bees really are tricky.