Can a 1999-P Nickel have a RPM? Did they still manually add mintmarks in 1999? The last RPM listing on CONECA is 1984. As always, thanks for entertaining my posts!
The MM was added to the master hub for circulation strikes starting in 1990 or 1991, so if 1 is a rpm they all are, so no added value. It looks like machine doubling(MD) to me, which affects a large area of the coin, in the same direction. Look at the inner loop of the last 9, you can see a trace of MD to the northwest, the same as the MM. PS, Proof Strikes started adding the MM to the master hub in 1985.