Wordpress wp_mail function sends email twice - wordpress

Question

I am using a cron event and adding a PHP code to send emails to users of my wordpress site. But due to some reason my wp_mail function is sending emails twice to all the users.
Here is my code, can anyone please tell me whats wrong with my code ?
$args = array(
'role' => 'employee',
'order' => 'ASC'
);
$all_users = get_users($args);
foreach ($all_users as $user) {
$to = esc_html($user->user_email) ;
// Always set content-type when sending HTML email
$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";
// More headers
$headers .= 'From: TEST <test#test.com>' . "\r\n";
$subject = "Regarding auto emails";
$message = "<p>Dear Employee/Consultant,</p>
<p >Please send in your submissions</p>";
wp_mail($to, $subject, $message, $headers);
}

Answer 1

You can write mail function in this way
if(wp_mail($to, $subject, $message, $headers)){ // Condition check if mail has been sent
continue; // Continue to next iteration
}

Answer 2

Your PHP looks okay to me.
I have had luck scheduling cron in WordPress using the approach shared here (duplicated below). And by structuring the mail function within loops as follows:
<?php
$to = 'email#website.com';
$subj = 'Subject';
$body ='
<br/>
Dear Recipient,<br/>
<br/>
Here is an email.<br/>
<br/>';
$headers[] = 'Content-Type: text/html; charset=UTF-8';
$headers[] = 'From: Website.com <email#website.com>' . "\r\n";
wp_mail( $to, $subj, $body, $headers );
?>
You can install a plugin like Cron Manager to verify that the cron event is scheduled. "custom_cron_event" (or whatever name you choose for your function) should be listed as a scheduled cron if you've activated the plugin and it is working correctly.
Cron schedule via plugin:
<?php
/*
Plugin Name: Custom Plugin
Plugin URI:
Description: Adds function on cron
Author:
Version: 1.0
*/
/*
* When this plugin is activated, schedule
*/
function activate_custom_cron(){
wp_schedule_event( time(), 'daily', 'do_custom_cron_event');
}
register_activation_hook(__FILE__, 'activate_custom_cron');
/*
* When this plugin is deactivated, clear_schedule cron
*/
function deactivate_custom_cron(){
wp_clear_scheduled_hook('do_custom_cron_event');
}
register_deactivation_hook(__FILE__, 'deactivate_custom_cron');
/*
* Function
*/
function custom_cron_event() {
/*
* This is where your function goes
*/
}
add_action( 'do_custom_cron_event', 'custom_cron_event' );
?>