Posted on behalf of Pamglos:
My bees swarmed on 19th June and today, only six days later, they have swarmed again. They were both large swarms and the second swarm has gone to exactly the same spot as the first one. My beek friend suspects that there were 2 queens living in my hTBH, is this likely? Or is the second swarm a cast, or overswarm? Previous comment says a 7 to 10 day period is normal for a cast, is six days too short a period?