Very Rare 8 Reales

I think you are refering to the Potosi Mint which had a big scandal over underweight coins occuring in the 1640's and maybe even earlier. The mayor of Potosi as well as one of the mint assayers and possibly others lost their heads in 1654 after the Royal investigation. After the scandal broke the design on all cobs minted in Lima and Potosi was changed and the King decreed that all the debased cobs be turned in for either melting or devaluation. As a result most of the 4 and 8 reales from Potosi from the 1640's were melted. The King declared all 8 reales minted from 1649 until the start of the new design in 1652 be valued at 7.5 reales and cobs predating 1649 were valued at 6 reales and had to be counterstamped at the mint to show their reduced value. But errors of this magnitude on Pillar dollars are very rare. This had become the coin of the world and the Kings reputation was at stake. I am only aware of 2 others, "EST IND" for "ET IND" on an Mo 1745 Half Real and VRTA for VTRA on the 1768JR Potosi 8 reales. I have never seen the 1745 in person but I have seen the 1768 at a coin show in Long Beach.