Why do you expect the voting algorithm to make the same decision when the voters make different decisions? If the addition of Option C causes supporters of Option A over Option B to decrease the difference in their scores between A and B more than the supporters of Option B over Option A, it can shift the algorithms output from Option A to Option B.
Why do you expect the voting algorithm to make the same decision when the voters make different decisions? If the addition of Option C causes supporters of Option A over Option B to decrease the difference in their scores between A and B more than the supporters of Option B over Option A, it can shift the algorithms output from Option A to Option B.