Illusion of Choice

• WWizards of the Coast2016-08-23
  Official Ruling
  If multiple players cast Illusion of Choice during the same turn, the controller of the one that resolved most recently will choose how each player votes that turn.
• WWizards of the Coast2016-08-23
  Official Ruling
  If another player controls Ballot Broker, that player first takes their “normal” vote with you choosing the result, then that player decides whether they are taking the additional vote. If there is an additional vote, you again choose the result.

Rulings via Scryfall