I have found several teams that have 2 club leaders. How is that possible?

I have come across this too and wondered the same thing. Support says it is not possible but I have asked the leaders of one of the teams and she says that she and the other leader switched a bunch of times over the course of a few years and then one day they found themselves both leaders and were no longer able to switch with each other. My team mate and I have been switching every day for the past two weeks and then ten times tonight trying to see if we could both become club leaders but nothing has happened yet. We will continue to switch daily until it hopefully does finally happen though.