The Piezos are able to measure the velocity of each hit based on the amount of vibration. The sketch even allows me to create a minimum velocity needed to send a MIDI signal. It seems like the code should be able to be altered to only allow a single MIDI note to be registered at a time (the note from the piezo with the strongest signal/vibration). Or am I missing something?
I should also note that currently, using the filter already built into the code, hitting the piece of wood only sends a signal from the nearest coupled of piezos. I used the Arduino Serial Monitor and recorded the data from various hits. It appears to be constant that the piezo nearest the point of contact for each hit sends the greatest value for the Velocity variable.