Now that's why I asked this earlier:
Is the mechanism for matching thrust demand to engine fuel flow open loop or closed loop. What I mean is, in the event that engine EPR/N1 is not what is being commanded by the thrust levers, does the fuel control unit keep trying to increase fuel flow until it is, or does the fuel metering unit simply set a fixed fuel flow and expect the engine to accelerate to an EPR setting concomitant with it?
If both fuel control units set the same fuel flow, then both engines *should* provide the same thrust. If there is any mis-setting, the result is the same on both engines, although not what has been commanded.