The radiogroup of cloned radio is not updated

<zk>
  <div>
      <radiogroup id='rgLineType'>
        <radio label='application'/>
        <radio label='comment'/>
        <radio label='include'/>
        <radio label='#include'/>
    </radiogroup>
    <separator/>
    <label id='info'/>
    <separator/>
    <button label='Clone radiogroup' onClick='CloneRadiogroup(event)'/>
    <separator/>
  </div>

<zscript>
void CloneRadiogroup (Event event)
{
	Radiogroup rgNew = rgLineType.clone();
	rgNew.setId(null);
	info.setValue ("name of source radiogroup is [" + rgLineType.name + "], name of clone is [" + rgNew.name + "]. seems different, but it is rendered as same name as the source: Click radio in the one radiogroup will clear selection in another radiogroup");
	event.getTarget().getParent().appendChild (rgNew);
}
</zscript>
</zk>