What is the result if a courtesy runner runs for both F1 and F2 in the same half-inning?

In a baseball or softball context, the role of a courtesy runner is specifically designed to allow a player who is on base, particularly a pitcher (F1) or a catcher (F2), to have a substitute runner in situations where running may be physically taxing for them. However, the rules state that a player can only serve as a courtesy runner for one player per half-inning.

If a courtesy runner is called to run for both the pitcher and the catcher within the same half-inning, it constitutes an illegal substitution. According to the regulations governing the use of courtesy runners, this action results in the courtesy runner being declared out, since one player cannot occupy the role of courtesy runner for multiple players at the same time in a given half-inning.

Understanding this rule ensures that players and coaches maintain compliance with the game’s structure and helps in reinforcing sportsmanship and fair play.