The purpose of the star in the serial number of a replacement is somewhat anachronistic. Its purpose was to alert the first user of a pack of notes (usually someone in the banking channels) as to why the serial numbers on some of the notes in the pack may be out of sequence. If you have ever read a BEP band you will understand what this means. I doubt anyone in the banking channels would pay much attention to an out of sequence note in a fresh pack today.
If the damaged note was replaced with a note with the same serial number there would be no reason for the star in the serial number as the numbers in the pack would be in sequence.
Replacing a defective note with one of the same serial number is referred to by the BEP as the "make up" system of replacements. On small size notes the make up system was only used on Nationals. The replacements were done by hand and can be identified by the font of the numbers and the fact that they are often misaligned. The make up system was also used for the printing of Defense and War Savings Bonds but these were machine numbered.