DimensionChangeEvent firing twice in a row

Question

The DimensionChangeEvent seems to fire twice in a row.
Once for the width and again for the height.
My thinking it should only fire once.
What is the use case for this behavior?
pPlayer.addEventListener( DimensionChangeEvent.DIMENSION_CHANGE, mDimensionChange );
============ First event ================
mDimensionChange [Event type="dimensionChange" bubbles=false cancelable=false eventPhase=2]
evt.newWidth = 600
evt.newHeight = 0
evt.oldWidth = 0
evt.oldHeight = 0
evt.currentTarget.width =  600
evt.currentTarget.height =  0
evt.currentTarget.view.calculatedWidth =  600
evt.currentTarget.view.calculatedHeight; =  800
============ Second event ================
mDimensionChange [Event type="dimensionChange" bubbles=false cancelable=false eventPhase=2]
evt.newWidth = 600
evt.newHeight = 800
evt.oldWidth = 600
evt.oldHeight = 0
evt.currentTarget.width =  600
evt.currentTarget.height =  800
evt.currentTarget.view.calculatedWidth =  600
evt.currentTarget.view.calculatedHeight; =  800

Answer 1

====== firing twice code ============
pPlayer.addEventListener(ViewEvent.DIMENSION_CHANGE, mDimensionChange);
====== code per your request ============
I now get a compiler error on the addEventListener:
pPlayer.addEventListener(ViewEvent.MEDIA_SIZE_CHANGE, mDimensionChange);
1119: Access of possibly undefined property MEDIA_SIZE_CHANGE through a reference with static type Class.
The online ViewEvent docs don't show a MEDIA_SIZE_CHANGE:
DIMENSION_CHANGE
Constant
public static const DIMENSION_CHANGE:String = "dimensionChange" 
The ViewEvent.DIMENSION_CHANGE constant defines the value of the type property of the event object for a dimensionChange event.
VIEW_CHANGE
Constant
public static const VIEW_CHANGE:String = "viewChange" 
Language Version:
ActionScript 3.0
Product Version:
OSMF 1.0
Runtime Versions:
Flash Player 10, AIR 1.5
The ViewEvent.VIEW_CHANGE constant defines the value of the type property of the event object for a viewChange event.