Replicate multiple-input-value bug in media modal

gistfile1.txt

/*
 *In plugin file or functions.php add the following code to create new form fields in your media modal 
 */
 
 function multiple_input_field( $form_fields, $post ) {
 $foo = get_post_meta( $post->ID, 'foo', true );
 $form_fields['foo'] = array(
    'label' => 'Is Foo',
    'input' => 'html',
    'html' =>
        '<input type="checkbox" id="attachments-'.$post->ID.'-foo" name="attachments['.$post->ID.'][foo][]" value="1"'.($foo ? ' checked="checked"' : '').' /> One</label></br>
        <input type="checkbox" id="attachments-'.$post->ID.'-too" name="attachments['.$post->ID.'][foo][]" value="2"'.($foo ? ' checked="checked"' : '').' /> Two</label></br>
        <input type="checkbox" id="attachments-'.$post->ID.'-three" name="attachments['.$post->ID.'][foo][]" value="3"'.($foo ? ' checked="checked"' : '').' />Three</label>  ',
    'helps' => 'Choose one or many'
    );
    return $form_fields;
 }
 
 add_filter( 'attachment_fields_to_edit', 'multiple_input_field', 10, 2 );
 
 /*
  * save fields
  */
  function admin_attachment_field_multiple_values_save() {
  
      $post_id = $_POST['id'];
      $foo = $_POST['attachments'][$post_id ]['foo'];
      
      if( isset( $_POST['attachments'][$post_id ]['foo'] ) ){
             update_post_meta($post_id , 'foo', $foo);
      }
} 

add_action('wp_ajax_save-attachment-compat', 'admin_attachment_field_multiple_values_save', 0, 1);