2008 Penny "8" Weak Doubling

What you have is a split plating doubling, it is not a true Hub doubling.

Sure. Here is the definition of the Split Plate Doubling.

http://www.error-ref.com/split-plate-doubling/

Split plating doubling is found where the strike was strong that it splits the plating. Your coin is not an example of that. What you have is called Die Deterioration Doubling. (die wear) Die wear always moves towards the closest rim. The single squess dies have a lot of this going on with them. Here are a few examples:





Why is this different than doubled dies? When you look at the last image, you can see the deterioration on the right of the date, but note, the fields are the only thing affected. Note the devices. So when the die begins to age it starts on on an area and sometimes you can find a coin with all areas affected. (Keep those for educational purposes for other new collectors.) A doubled die has the doubling on the die. It was created during the die creation process.
So a doubled die is a variety.
Machine Doubling is a striking event.
And Die Deterioration is a die event. (part of aging)