You cannot have two pulse inputs on either an emonTx or an emonPi given the present design. Although the processor does have two interrupt inputs, which are what we use, one interrupt is used for the radio, leaving the possibility of only one pulse input.
Therefore, to monitor two flashing LEDs, you need two devices.
A current transformer on the grid connection in conjunction with a voltage transformer is able to both measure the current and by comparing the phase relationship between current and voltage, determine both the real power and the direction of power flow.
An optical pulse sensor is both accurate and historical - it is as accurate as your supplier’s meter, but it can only show energy that has already passed through it. It cannot give an indication of power until some quantum of energy has been measured over some period of time and you are able to calculate the rate of change of energy over time.
A current transformer is capable of calculating power from one mains cycle to the next, but as an analogue device having inherent errors, it must be calibrated carefully. When that has been done, it should be good to within about 1% of your supplier’s meter.
Each is better than the other, depending on what you want to know from it.