Drag and Drop game with only two targets

I created a drag and drop activity where their are five boxes that are supposed to go in to two columns in any order. I used this tutorial to build it http://www.flashclassroom.com/docs/d...tsflashcs3.pdf

The problem is that the tutorial shows you how to make a target for each mc which has worked for all the activities I've made except for this one where I need only two targets. How would I change it so I can have multiple mc's drop on to one target?

This is my AS:

var score:Number = 0;

var objectoriginalX:Number;
var objectoriginalY:Number;

growing_mc.buttonMode = true;
growing_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickupObject);
growing_mc.addEventListener(MouseEvent.MOUSE_UP, dropObject);

gorging_mc.buttonMode = true;
gorging_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickupObject);
gorging_mc.addEventListener(MouseEvent.MOUSE_UP, dropObject);

dormancy_mc.buttonMode = true;
dormancy_mc.addEventListener(MouseEvent.MOUSE_DOWN , pickupObject);
dormancy_mc.addEventListener(MouseEvent.MOUSE_UP, dropObject);

cystform_mc.buttonMode = true;
cystform_mc.addEventListener(MouseEvent.MOUSE_DOWN , pickupObject);
cystform_mc.addEventListener(MouseEvent.MOUSE_UP, dropObject);

hosttrans_mc.buttonMode = true;
hosttrans_mc.addEventListener(MouseEvent.MOUSE_DOW N, pickupObject);
hosttrans_mc.addEventListener(MouseEvent.MOUSE_UP, dropObject);

function pickupObject(event:MouseEvent):void {
event.target.startDrag(true);
event.target.parent.addChild(event.target);
objectoriginalX = event.target.x;
objectoriginalY = event.target.y;
}
function dropObject(event:MouseEvent):void {
event.target.stopDrag();
var matchingTargetName:String = "target" + event.target.name;
var matchingTarget:DisplayObject = getChildByName(matchingTargetName);
if (event.target.dropTarget != null && event.target.dropTarget.parent == matchingTarget){
event.target.removeEventListener(MouseEvent.MOUSE_ DOWN, pickupObject);
event.target.removeEventListener(MouseEvent.MOUSE_ UP, dropObject);
event.target.buttonMode = false;
event.target.x = matchingTarget.x;
event.target.y = matchingTarget.y;
score++;
scoreField.text = String(score);

} else {
event.target.x = objectoriginalX;
event.target.y = objectoriginalY;
}
if(score == 5){
response_mc.gotoAndStop(2);
}
}