Hi everyone, both Bee-l & IBList,
Re: Tom's post to both lists

To clear up a few points re: Two Queen System.
Here goes :-

If you overwinter colonies on two brood boxes then:-
In spring/early summer
 -  start with a strong, healthy, queen-right colony.
 -  separate the two boxes.
 -  find the queen (yes, I know!!!) and put her/make sure she's in the
bottom box.
 -  most brood and stores will be in the top box, - depending on your
judgement, swap a couple of frames of stores to the bottom box if you feel
that the (parent) colony will need it.
 -  Put an effective queen excluder on the bottom brood chamber - the parent
colony.
 -  Put a super/extracting box/whatever above the excluder, on top of the
bottom brood chamber.
 -  Put a division board/floor on top of this to separate the parent colony
from what will become the new (child) colony (make sure you provide an
entrance to the new colony).
 -  The child colony needs a queen, so - introduce a mated queen with
characteristics you desire (Hurray!), or, make sure the child colony has 2-3
good looking queen cells (Hiss!), or, make sure the child colony has a frame
containing eggs (Booo! Hiss!).
 -  Bearing in mind that foraging bees from both colonies will return to the
parent colony, if the child colony seems light in population, temporarily
block its entrance with grass (which will dry and fall out) to retain as
many as possible of its foraging force. Do this anyway if you are relying on
queen cells or emergency cells.
 -  Later, assuming you now have two separate, queen-right colonies (it
doesn't always go smoothly, obviously), remove the super and place a 1/4"
wooden baton (or piece of twig) across each of the front corners of the
bottom brood box above the excluder.
 -  Remove the division board/floor from under the child colony's  brood
chamber and place the colony down on top of the parent colony's excluder  -
the batons provide a separate entrance to the child colony.
 -  Take a can of air freshener (what do you mean, you forgot to bring any?)
and spray into the gap between the top and bottom brood chambers. If you are
a traditionalist or have plenty of time and it's not windy, you can use
newspaper between the two colonies and between the child colony and the
super which you are about to replace.....
 -  Put another effective queen excluder above the child colony.
 -  You can safely put another empty super/extracting box on immediately
above this excluder before replacing the (presumably) half filled or half
pulled box that was on previously as this unit will now really start to
motor if there is any sort of a flow.
 -  Continue to put on supers before you think they need any.

For colonies overwintered on a single brood box, you will need to provide
another brood box and make up a nucleus to serve as the child colony  or
combine colonies, possibly from different apiaries.

Points to note in vertical Two Queen Systems (even three or four queen
systems, the sky's the limit!):-

Why do it?
 - In partial answer to Rex Boys on IBlist and other sceptics, yes,  it
seems that the young bees especially, from both colonies co-operate on
essential tasks such as feeding brood, hygiene, maintenance and, most
important to us, on comb building. They also mediate transference of queen
pheromone, so a two queen system should no longer be thought of as two
separate colonies but as one larger system.
Regarding honey production, most honey stores and nectar gathered will be
moved out of the brood chambers and stored in the supers to provide room for
the queens to lay. This results in sheets of brood in the brood chambers
with little or no arches of honey over the brood nests and more lovely honey
for the beekeeper.

Problems and NoNos

Try and ensure that the queen in the upper brood chamber is younger and more
prolific than the lower queen, otherwise her brood space is likely to become
filled with honey/nectar (honey-bound).
Don't put the supers between the two brood chambers, ie with the child
colony on top, as the top brood chamber is liable to become honey-bound in a
heavy flow no matter the profligacy of the queen.
When you remove a crop, be very aware that there is liable to be very little
food in the brood boxes and the bees will need fed if there isn't a flow on
and you don't leave them something.
Depending on your breed of bees and size of brood chamber, running a two
queen system can put enough pressure on the bees to increase their
predeliction  to swarm and, it seems, that when one part of a two queener
swarms it is more than likely that the other joins in (enough there for
someone's PhD). So check regularly for swarm cells (yes, I know it means all
the backache of lifting all those nearly full boxes of honey!) and take
appropriate action.

And finally -
To achieve the grail of beekeeping, ie- requeening with a proven, desirable
young queen to stand you in good stead for next year, remove the excluder
between the parent and child colonies before the end of the season -
allowing the young queen (9 times out of 10) to do a hatchet job on the old
queen, giving the expanded force of foragers an opportunity to gather a
large, late crop (eg. heather) and ending up with a well-found colony for
wintering down.

Have fun and good luck,
Rick Brodie.