Changing frames in a class

So I'm working on a pretty basic game at the moment. When I press the down key, I want the character (at the moment, just a square) to slide underneath obstacles. I have the standing animation as one frame and the sliding as another within the same class, but when I press the down key, it switches to the second frame yet another object on the first frame remains over top. I suspect that because I created the square like so:

//Create square

          var newSquare:Number = 1;

          var Square:square = new square;

          Square.x = 50;

          Square.y = 180;

          stage.addChild(Square);

that it's constantly creating new squares overtop the one that's sliding. The code for the sliding is as follows:

//Slide

          var down:Boolean = false;

          stage.addEventListener(KeyboardEvent.KEY_DOWN, _slideDown);

          function _slideDown(e:KeyboardEvent):void {

                    if (e.keyCode == 40) {

                              down = true;

                    }

          }

          stage.addEventListener(KeyboardEvent.KEY_UP, _slideUp);

          function _slideUp(e:KeyboardEvent):void {

                    if (e.keyCode == 40) {

                              down = false;

                    }

          }

          stage.addEventListener(Event.ENTER_FRAME, _slide);

          function _slide(e):void {

                    if (down == true) {

                              Square.gotoAndPlay(2);

                    }

                    if (down == false) {

                              Square.gotoAndPlay(1);

                    }

          }

If I'm right about generating infinite squares, could someone help me fix it? I tried using a conditional and number variable and then changing the number when the square was created, but that didn't help. If I'm not right, any other help would be appreciated.