Sorry for the Zombie post, but I actually had this same problem and did implement a “double tap” rule that worked around it for the last couple years (thanks to these suggestions).
I’m happy to report that the work around appears to no longer be necessary with the insteon beta binding from jeshab. It adds triggered events that don’t appear susceptible to the all-buttons-at-once problem like the current binding. Thought I’d share in case anyone else lands here.