PHP Script is creating an empty row along with desired row

Currently using React for frontend, php for backend with XAMPP/Apache. When I send a POST using the fetch API, It creates two rows in my table, one empty and one with the correct details. I have verified that the js function only runs once (strict mode not the problem), and verified that the php code runs twice. I am fairly new to php and fetch and am at a loss as to why this is happening.

First row is made incorrectly on first run, not sure how. Second is correct.

register.php:

<?php
require_once('cors.php');
require_once('db_connection.php');

$data = json_decode(file_get_contents('php://input'), true);

$username = $data['username'];
$email = $data['email'];
$password = $data['password'];

$street = $data['street'];
$state = $data['state'];
$country = $data['country'];

$fname = $data['fname'];
$lname = $data['lname'];
$phone_number = $data['phone'];

$hashed_password = password_hash($password, PASSWORD_DEFAULT);

error_log(print_r($country, TRUE)); // prints twice
$sql = "INSERT INTO User (Email, `Password`, Street, `State`, Country, `First Name`, `Last Name`, `Phone Number`, Username)
 VALUES ('$email', '$hashed_password', '$street', '$state', '$country', '$fname', '$lname', '$phone_number', '$username')";
$result = $conn->query($sql);

if ($result === TRUE) {
    echo json_encode(array("success" => "Account Created Successfully"));
} else {
    echo json_encode(array("error" => "There was an error in your submission"));
}

$conn->close();
?>

register.jsx excerpt

  const onSubmit = e => {

      e.preventDefault() // only prints once
      console.log('hello')
      if (password === rePassword) {

        fetch('http://localhost/teashop/php/register.php', {
            method: 'POST',
            headers: {
              'Content-Type': 'application/json'
            },
            body: JSON.stringify(formData)
          })
          .then(response => response.json())
          .then(data => {
            
            if ('success' in data) {
              setDisplay('login');
            }
          })
          .catch(error => {
            console.error('Error fetching products:', error);
          }
        );