Did Earth's Twin Cores Spark Plate Tectonics?

I just came across this on Yahoo with a link to Discovery and found it quite interesting. It is very "out there" in my opinion but Earth could be even more unique than we ever imagined if this is true.

I'm curious as to what all the earthquake buffs think about this.

Very interesting theory none the less...

"Now a new theory aims to rewrite it all by proposing the seemingly impossible: Earth has not one but two inner cores.

The idea stems from an ancient, cataclysmic collision that scientists believe occurred when a Mars-sized object hit Earth about 4.45 billion years ago. The young Earth was still so hot that it was mostly molten, and debris flung from the impact is thought to have formed the moon."

dsc.discovery.com...

hi
makes me think that the hollow earth may be true.
strangemaps.wordpress.com...
Will see what other's have to say.

I have a few points that seem to be contradictory to this theory:

1) why wouldn't the two cores, under the immense pressure of the gravity of a planet, combine into one core

2) the rocks brought back from the moon did not come from Earth, they share none of the common traits of rocks here and furthermore could not have formed here

3)the presence of two cores, i.e. two exceptionally massive areas inside of the Earth would manifest itself in a planetary wobble wouldn't it? I would also think that many other gravitational quirks would be a dead giveaway.