if you have 3 RPi’s (
A, B, A+B), the feed to Flightaware will be only from those RPi’s on which you install Piaware data feeder.
However if you have installed Piaware data feeder on RPi
A+B, then you will have to turn MLAT off on this RPi. In case you dont turn off MLAT, the Flightaware System will detect merged feed and will disable MLAT
For non-merged RPi’s
A & B, you can feed Flightaware with MLAT turned ON.