var container:MovieClip = createEmptyMovieClip("container", getNextHighestDepth());

var mcLoader:MovieClipLoader = new MovieClipLoader();

mcLoader.addListener(this);

 

function onLoadInit(mc:MovieClip) {

        duplicateMovieClip(mc,"m123",1234);        

        trace("duplicateClip: " + m123); //undefined

}

mcLoader.loadClip("items.png", container);