I built a double queen hive and installed two packages of Italians last month. I call my hive a "Kerkoff Knock off" hive. I will give you this link, http://www.beesource.com/forums/showthread.php?234503-kerkhof-hive-plans
it is a little more information about two queen hives, with a link to pictures of my hive. If you have questions or just want to talk, I respond on either forum.
hmm think I would like to try 1 of these H3 hive setups, I could build a top that would cover both stacks of brood boxes with a good seal over them and a single stack of honey boxes in the middle, be a fun winter project, just split a hive in early spring and have 1 side requeen its self.
I have a 2 queen that I set up this spring I used the stacked method Because of how small the nuc was. I took a hive after pollination 15th of May, there were about 13 frames of brood 15 with brood in them. I put the queen in the bottom box with 8 frames of mostly open brood and a honey and pollen for the other two and placed a box of empty drawn comb on top. The top box that had 7 frames with mostly sealed brood, I left 4 trames of brood 1 frame honey and pollen and placed it on its own bottom board. and made up 2 nucs. 1 with 1 1/2 frames of brood and 1 1/2 frame of honey and pollen the next with 1 frame of brood and 1 frame of honey and pollen and introduced a mated queen into each of the 3 nucs. checked that queen was released and laying. placed the 1 1/2 brood nuc in the nuc box on top of the single with the entrance the other way. Around the 1st of June Placed a queen excluder over single placed dadant super on, then a sheet of newspaper and queen excluder moved nuc frames into a standard hive body with drawn frames. followed by an other queen excluder and a dadant honey super and an inner cover with a bee entrance in the rim. Added suppers July 13 and August 2 the flow in some areas have stopped. so last boxes night still be empty.
and the little 1 frame nuc she has 9 frames of brood in the bottom super and 2 dadants one full the other 75 % full and caped.
The other system is the Miller method of two queen. Place two hives tight together on the same double stand you can have them as singles or double brood chambers. Place a queen excluder in the middle of the two hives and a sheet of news paper to slow introduction. supper and queen excluder are 1/2 on each hive and go up from there. You need 2 - 1/2 width lids to cover the outsides of the brood boxes. An advantage to this system is it gives you access to 5 frames in the brood chamber with out having to remove the honey supers. If you are using drone comb cull for mite control you have easy access to thous frames. You don't have a brood supper in the middle of your honey and the hives aren't so high.