I have heard many times of colonies with two queens and I think Danno even posted a picture of two queens on the same frame. While helping a friend go thru some of his hives, I was able to point out two queens on the same frame a couple inches apart and totally uninterested in each other. Normally when I find a queen I am thru looking so I assume this is more common than we think.
Cool
Hopefully, we'll see more of it. Given the seemingly shorter productive lives of queens these days, I would hope the bees would respond by keeping more than one.
I think it happens more times than we think.
Mother and daughter team. Though they don't stay that way for long.