Hope this helps in deciphering the two-time repetition of the "This Card is NOT a Match!" statement.
No, not really.
Putting each { on a new line, and using Tools + Auto Format would help.
So would including the value of n in the output:
Serial.print("Card ");
Serial.print(n);
Serial.println(" is NOT a Match!");
This way, if you see:
Card 0 is NOT a Match!
Card 1 is NOT a Match!
then we know one thing.
If you see
Card 0 is NOT a Match!
Card 0 is NOT a Match!
or
Card 1 is NOT a Match!
Card 1 is NOT a Match!
then we know something else.