I have a hive with two regular sizes hive bodies, and two queens living in them peacefully side by side without a queen excluder. It has been going on for over a month now. First I though that it is the same one but now I know for sure they are different ones. One is a little bigger in size, and I am not sure if she is the older one, also she lives downstairs. Both of queens are laying perfectly good. Now, I would like to ask what is the best way to split them up.
How old is the older queen? I assume they're mother and daughter. This sounds like queenright supersedure, where the bees 'decide' the old queen is failing, and raise a new one. They lay side by side for a while, then eventually the older disappears. I have heard of the two still being together after a year, but this would be most unusual. Normally, the older queen is in the process of being replaced, and you don't know how many eggs, if any, she's laying. It's probably best to let them be.