[bes]

<script src="http://code.jquery.com/jquery-latest.min.js"></script>

<input type="radio" name="rg1" checked>
<input type="radio" name="rg1">
<input type="radio" name="rg1">
<br>
<input type="radio" name="rg2" checked>
<input type="radio" name="rg2">
<input type="radio" name="rg2">

<script>
jQuery(function ($) {
	$(':radio[name^="rg"]').bind('change', function () { 
		var rg1 = $(':radio[name="rg1"]');
		var rg2 = $(':radio[name="rg2"]');
		if ($(this).attr('name') == 'rg1') {
			rg2.eq(rg1.index(this)).attr('checked', 'checked');
		} else {
			rg1.eq(rg2.index(this)).attr('checked', 'checked');
		}
	});
});
</script>