title: How to add filter or hook for "woocommerce_add_to_cart"
body: <p><img src="https://i.stack.imgur.com/eGtvC.png" alt="enter image description here"></p>
  
  <p>I want add to cart two product at the same time, one is original (current) product and second is from drop-down list</p>
  
  <pre><code>add_action('woocommerce_add_to_cart', 'custome_add_to_cart');
  $cnt=2
  function custome_add_to_cart() {
      global $woocommerce;
        $cnt = $cnt + 1;
        echo $cnt."X";
        echo $p_id=$_POST['assessories'];
      $woocommerce-&gt;cart-&gt;add_to_cart($p_id, 1);
  
  }
  </code></pre>
  
  <p>Output:-
          As you can see in output image below , it adding same drop-down item many time in cart but i want only 1 quantity to add to cart. it seems that add_to_cart function run many times.
  What should i do or how to add filter with passing second drop-down product as parameter to add to cart  function ? so i can add this product also in cart.</p>
  
  <p><img src="https://i.stack.imgur.com/Pi0eo.png" alt="enter image description here"></p>