It's probably worth noting that the thermocouples that are used to measure turbine gas temperatures are not the most accurate way to measure temperature.
RTD's - Resistive Temperature Device - are very accurate, but can't handle the temperature ranges in a turbine (they work great for things like ambient temperature and total air temp), and are really easy to fault detect. Thermocouples not so much.
It's quite possible that the thermocouple on one engine isn't reading accurately.