[jQuery] buggy .add()

Hi there!
Maybe I missed smt, but seems like this is a bug:
<div id="#xxx">xxx</div>
<div id="#yyy">yyy</div>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
var e1 = document.getElementById('yyy'),
e2 = document.getElementById('xxx'),
$e = $(e1);
alert($e.length);
$e.add(e2); // or $e = $e.add(e2);
alert($e.length);
</script>