It looks like you ping one sensor, ping the second sensor, then listen for the echo on the first sensor, then listen for the echo on the second sensor.
The sensors can't discriminate the source of an echo, so the method is probably flawed.
It looks like you ping one sensor, ping the second sensor, then listen for the echo on the first sensor, then listen for the echo on the second sensor.
The sensors can't discriminate the source of an echo, so the method is probably flawed.