25c ALFONSO XII HANDSTAMPED "REINTEGRO"
This is a revenue handstamp, meaning RESTITUTION. This is the first time that I have encountered this handstamp on a postage stamp. I am aware of Stamped Paper for Reintegros which together with Stamped Paper for Multas (Fines) was created by the Proclamation of the Governor General issued on April 20, 1853.

Arnold Warren devoted Chapter 9 of his unpublished studies on Philippine revenues to Stamped Paper for MULTAS, REINTEGROS and PAGOS AL ESTADO (Payments to the State). Please click HERE for this chapter.

I maybe wrong or probably missed it but I have combed Warren's unpublished manuscript and found no mention of a "REINTEGRO" handstamp on postage stamps.