Mark wonders about separating the queens in two-queen hives.

Two-queen hives are run with either the queens side-by-side, or up and down.
If up and down, queen separation is really easy as a plain bottom board will
do the job.  But so will a piece of plywood.

The difficulty with up and down is that the top hive (with supers) must be
removed every time the beekeeper wants to add a super to, take a super off,
or inspect the lower hive.  The most use I have seen with up and down
two-queen hives has been to build really strong hives for comb honey
production.  This is something I do not recommend, as reduction to one hive
and adding comb honey supers means the beekeeper is constantly fighting the
swarming tendency.

Side-by-side two queen hives work extremely well.  The queens are kept
separated by plywood, hardboard, or something similar.  It is best to insert
these into 1/4" deep slots sawn into the wood before the hives are
assembled.  The same slots should be cut into supers.

The best method I have seen involved the slots and plywood and a common
bottom board.  However, the bottom board had a lug inserted so that the
plywood insert sat into a slot cut into it.
Supers had just the slots, but the inserts sat right on top of the inserts
of the hive or super below.  The precision required to get the slots in the
right place meant that the new wood had to be purchased from the same
manufacturing dealer at the same time.

This beekeeper starts these two-queen hives in the early spring with splits.
Above he puts either one deep or two mediums with foundation.  This gives
him sufficient new frames for normal replacement of old comb.  When the
foundation is well drawn, which doesn't take long, he puts on a queen
excluder and then puts on Ross Round(tm) supers.  When I saw them, he had
almost 50 two-queen hives with 5-6 Ross Round(tm) supers on every one!  (The
purpose of the queen excluder is to keep the queens from finding each other
in the unrestricted supers.)  Apparently the bees can mix together above the
excluders without any difficulties.

Up and down two queen hives are a tremendous amount of work.  Side by side
two queen hives require some accurate wood modification.  Both can result in
unbelievable amounts of production.

Lloyd
Lloyd Spear, Owner, Ross Rounds, Inc.  The finest in comb honey production.
www.rossrounds.com