Your question is Win Probability With Reroll Ties. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Three players roll a fair six-sided die. The player with the highest unique number wins, and if there is a tie all players reroll. What is the probability of winning for each player, and how does it change if one player is guaranteed to roll a four?