XML object decoupling

Hi Gang:
I'd like to use the xml result from an httprequest as the dataproviders for 2 separate controls. :

// function PositionData gets positions titles from table positions
public function PositionData(event : ResultEvent) :void {
var xmlResult:XML = event.result as XML;
posGridXml=xmlResult;
posCmbXml=xmlResult;
posCmbXml.prependChild('any');

As you see, I assign the result (xmlResult) to two xml variables (posGridXml and PosCmbXml) , then add the node value 'any' to one of them. My problem is that both XML vars show the new value when they are loaded into the controls.

Obviously the 2 new xml variables are referencing that original xmlResult. How can I decouple the new variables so that a change to one doesn't change the data in the other?

Thanks,
KW