Does Morde have a 100% chance of getting pick in One for All?

When me and a friend play One for All, my friend would always vote for morde to troll. I would always vote for a different champ, but every single time we would end up playing morde. I'm pretty sure it is a bug in the champ select because we have played morde over 5 times in a row. Each time the champ select stated that morde had a 20% chance for being selected except for 1 game where he had a 40% chance.