Flash MX 2004.
document.duplicateScene()
None.
A Boolean value: true if the scene is duplicated successfully; false otherwise.
Method; makes a copy of the currently selected scene, giving the new scene a unique name and making it the current scene.
The following example duplicates the second scene in the current document:
fl.getDocumentDOM().editScene(1); //Set the middle scene to current scene.
var success = fl.getDocumentDOM().duplicateScene();