I have a D’Lay and a Tap-Tempo PCB set ready building, but they are in my build queue and not seen the bench yet.
Looking at the schematics for each, my concern is that with one Tap-Tempo for two D’Lay circuits, would there be a need for DC decoupling between them. I don’t know the TTG-Taptation IC well enough to decide if DC decoupling is required or not. I also do not think there would be any harm in trying. I suggest following the build docs for each and TRY the dual connection to the second D’Lay. AFTER FIRST ENSURING BOTH D’LAY PCBS WORK AS THEY SHOULD WITHOUT THE TAP-TEMPO.