Detaching Drupal Behaviors of another module
we faced the same issue here we are using lightbox module what we did is we dint used any extra module in common we wrote a Behaviour to add a external class and added condition to when colorbox is added remove external class     

Define your base URL in any module in it 

"Drupal.settings.baseUrl" 

/* external links*/
 Drupal.behaviors.external_link = {
    attach: function (context, settings) {
      $("body .view-content a").once(function() {
                    var anchorlink = '';
                    anchorlink = jQuery(this).attr('href');
                    if(anchorlink != "#" &amp;&amp; !$(this).hasClass('lightbox-processed'))
                    {
                        if(!(anchorlink.lastIndexOf('http') == -1) &amp;&amp; anchorlink.lastIndexOf(Drupal.settings.baseUrl) == -1 &amp;&amp; !jQuery(this).hasClass("external"))
                        {
                            if($(this).parent().hasClass('lightbox-processed')){
                                    jQuery(this).removeClass("external");
                            }else{
                                    jQuery(this).addClass("external");
                                    var targ = "_blank";
                                    jQuery(this).attr("target", targ);

                            }
                        Drupal.attachBehaviors();
                        }
                    }
      });
   }
  };


instead of lightbox-processed replace your class
hope this will help you :)