3-3. Doubt as to Procedure (From USGA Rules of Golf)

a. Procedure

In stroke play only, when during play of a hole a competitor is doubtful of his rights or procedure, he may, without penalty, play a second ball. After the situation which caused the doubt has arisen, the competitor should, before taking further action, announce to his marker or a fellow-competitor his decision to invoke this Rule and the ball with which he will score if the Rules permit.

The competitor shall report the facts to the Committee before returning his score card unless he scores the same with both balls; if he fails to do so, he shall be disqualified.

b. Determination of Score for Hole

If the Rules allow the procedure selected in advance by the competitor, the score with the ball selected shall be his score for the hole.

If the competitor fails to announce in advance his decision to invoke this Rule or his selection, the score with the original ball or, if the original ball is not one of the balls being played, the first ball put into play shall count if the Rules allow the procedure adopted for such ball.

Note 1: If a competitor plays a second ball, penalty strokes incurred solely by playing the ball ruled no to count and strokes subsequently taken with that ball shall be disregarded.

Note 2: A second ball played under Rule 3-3 is not a provisional ball under Rule 27-2.