Circuit with two Ultrasonic Sensors.

Other Hardware Sensors
2

Probably best to alternate between the two rather then to try to ping both simultaneously:

  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPin, LOW);
  pinMode(inPin, INPUT);
  duration = pulseIn(inPin, HIGH);

  pinMode(pingPink, OUTPUT);
  digitalWrite(pingPink, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPink, HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPink, LOW);
  pinMode(inPink, INPUT);
  durationk = pulseIn(inPink, HIGH);