Copy Children From One Flex Container to Another

Okay, this shouldn't be so difficult but I'm having a helluva time with it. I have two canvases. All I want to have happen is when I add a child to canvas A I want it to also be added to canvas B at the same time. Sounds easy right, but for some reason it's only showing up in the second canvas, not the first. It's driving me crazy. Any ideas out there?

var imageContainer:WallItem = new WallItem();
...
WallModel.getInstance().dropArea.addChild(imageContainer);
WallModel.getInstance().navCanvas.addChild(imageContainer);

When I do this the item only shows up in the "navCanvas" but if I take out the second addChild it shows up fine in "dropArea." What am I missing?

Flex 4 Skinning Video

Looks like there is some very cool stuff coming in Flex 4 with regards to skinning components.