Drag and drop as3

Hi Im knew to animate I keep getting this error message 1021: Duplicate function definition. could someone help me please this worked for me before but has stopped working now 

Hat.addEventListener(MouseEvent.MOUSE_DOWN, fl_ClickToDrag_9);

function fl_ClickToDrag_9(event:MouseEvent):void
{
Hat.startDrag();
}

stage.addEventListener(MouseEvent.MOUSE_UP, fl_ReleaseToDrop_9);

function fl_ReleaseToDrop_9(event:MouseEvent):void
{
Hat.stopDrag();
}