Leader of a Big Family Glitch

Try this

1 and 2 are the same level. 1 has a little more exp than 2, adds 2 as jr. 1 idles and 2 passes 1's exp (but not level), adds 1 as jr., back and forth.

Or just have two people of the same level continuously add eachother.

OR maybe it happens if two people try to add eachother at the same time (both have the conformation bubble up) and confirm together.