I hope this can help all of those people who were wondering how this was done. It can also be done with photoshop. Please rate and comment!
About this creation
In the picture above you see a man jumping off a clone base onto a rock with a clone trying to shoot him down.
This is what the picture REALLY looks like. Here is a simple way using GIMP to erase it.
Here in GIMP you see an empty picture that the man and clone were on, you need to take a similar picture with the bricks and people OFF the base plate.
Next, open your picture with the man on the brick and paste it over the picture with no people on it.
Next you need to select your eraser tool and erase the brick.
To make it have more detail, zoom in and try to erase more of the brick that's hard to reach. (This is optional.)