Tom Barrett wants to know how to find second queen when requeening.
Queen excluders work great! Nail an all wire excluder to the bottom of
an empty hive body. Knock hive down to bottom box. Remove combs with
bees, and lean them against next hive. Place excluder box on top of  now
empty hive. Slide E - Box over to leave opening large enough to put comb
back in hive. Now shake bees off first comb into E-Box, place comb back
into hive, and slide it back under E-Box with hive tool and thumb.
Procede with other combs until all 9 or 10 are shaken and back in hive
under E-Box. Slide E-Box back over hive. Shake all of remaining combs
into E-Box. Bees will go down through excluder and onto brood below.
This leaves queen (queens) and drones above excluder. Scrape inside of
E-Box with hive tool if bees try to climb out. This is an easy
procedure, and can be done by any novice. It works just about every
time. I've found two queens in about 5-10% of the colonies. Good luck!
Mike