<script>
      var f1_src = "http://www.weibo.com";
      var f2_src = "http://www.douban.com";
      function openAtIframe()
      {
          window.open(f1_src, 'f1');
          window.open(f2_src, 'f2');
      }
  </script>

<div class="a" onclick="openAtIframe(f1_src, f2_src);"><a href="javascript:void(0);" >open 2 window</a></div>
<iframe name="f1" width="500" height="700"></iframe>
<iframe name="f2" width="500" height="700"></iframe>