Dr. Pedro P. Rodriguez wrote:
> I am kind of curious that you would not at least try to locate one of
> the queens when you join swarms.  It might be that both queens die in
> their "ducking it out contest" or the surviving queen might get hurt and
> not be quite as efficient.  Getting rid of one (it should not be
> difficult in a swarming environment to find one of the queens could save
> you that degree of difficulty).
 
I guess a lot of people would be more comfortable with the method you suggest, but here's my thinking and experience on the subject:
 
In large apiaries, swarms often combine naturally when they emerge from several hives about the same time.  These swarms can be huge (referred to as "barrel swarms") and have as many queens as there are hives contributing a swarm.  I've seen 4 queens in one large swarm.  My 19 pounder from earlier this year qualified as a small barrel swarm.
 
I have had very good success letting nature take it's course with multiple queens in swarms.  As a general rule, the surviving queen is not injured.  I also have no way to know which queen will perform better.  How would I choose the one to keep?  The big  healthy looking queen in a swarm may be old and running out of sperm or eggs even though she still looks good.  Quite often the queen in a swarm fails soon from old age.  My theory is that combining swarms gives better odds of ending up with a relatively young queen.   I assume that younger queens are more inclined to fight than older ones, and thus more likely to win.  Also, I suspect that the bees help with the decision about which queen will survive. 
 
I usually requeen swarm hives no later than Fall of the year I capture them anyway.
The exception to that is when I know the swarm emerged with a young or even virgin queen and she turns out to be a good one.  In that case I might give her an extra year.
 
Another reason I don't look for queens in swarms is that I prefer to get them in the box ASAP and quit bothering them so they can settle into their new home.  As I said in my previous post, 40 of 42 swarms this year have stayed put in my boxes, and I suspect they're less stressed by having to deal with multiple queens than they would be by my rummaging around looking for queens.  How many would I look for? How would I know when to stop looking?
 
The bottom line is honeybees are well designed to settle queen controversies.  They don't really need much help from me.
Michael