Die appears to have been reworked or altered in some way. Rather mysterious, it is similar to die deterioration.
From David Poliquin: The reverse P die degradation is the product of an improperly hardened working die. The cause of this ‘soft die’ is either die steel issues or improper annealing of the working die between hubbings from a working hub. An improperly hardened working die will appear normal, but will deteriorate prematurely under the forces of minting due to the die’s softened state.
This reverse die has also been spotted with a non-variety obverse in addition to the 1880 PUN-008.