Reference cirkit: https://app.cirkitdesigner.com/project/92846e97-70c3-4e48-bd21-e2beb951df20

Testing script:

const int STEP1 = 3;
const int DIR1  = 2;

const int STEP2 = 5;
const int DIR2  = 4;

const int ENABLE_PIN = 8;

const int STEPS = 1000;       // 5 revolutions
const int PULSE_DELAY = 300;  // Faster speed

void setup() {
  pinMode(STEP1, OUTPUT);
  pinMode(DIR1, OUTPUT);

  pinMode(STEP2, OUTPUT);
  pinMode(DIR2, OUTPUT);

  pinMode(ENABLE_PIN, OUTPUT);

  digitalWrite(ENABLE_PIN, LOW); // Enable both drivers
}

void loop() {
  // Both motors forward
  digitalWrite(DIR1, HIGH);
  digitalWrite(DIR2, HIGH);

  for (int i = 0; i < STEPS; i++) {
    digitalWrite(STEP1, HIGH);
    digitalWrite(STEP2, HIGH);
    delayMicroseconds(PULSE_DELAY);

    digitalWrite(STEP1, LOW);
    digitalWrite(STEP2, LOW);
    delayMicroseconds(PULSE_DELAY);
  }

  delay(1000);

  // Both motors backward
  digitalWrite(DIR1, LOW);
  digitalWrite(DIR2, LOW);

  for (int i = 0; i < STEPS; i++) {
    digitalWrite(STEP1, HIGH);
    digitalWrite(STEP2, HIGH);
    delayMicroseconds(PULSE_DELAY);

    digitalWrite(STEP1, LOW);
    digitalWrite(STEP2, LOW);
    delayMicroseconds(PULSE_DELAY);
  }

  delay(1000);
}