Stumbled upon a minor find. It seems syncing the moku clocks is enough to allow simultaneous demodulation of the 25 MHz phase modulation on the 775 light without referencing the signal.

EX: Sync moku clock via reference output on the back. Put 25 MHz 2V pp + 14 dB signal on Moku 4 output 3, going to EOM. Attempt to lock the other cavity, on a different moku, with no phase modulation signal output (laserlockbox.png, it thinks its making a 25 MHz signal, but the clocks are synced well enough to demod the other signal). Have to adjust the phase slightly but otherwise this just works. Prevents us from having to split this signal and feed it into each moku and then reference as external. Maybe this is obvious to others but I was suprised this worked. You get a slightly larger error signal peak to peak amplitude if the signal is coming from the moku you are using, but a small one (~8% increase).