Plank by Plank

The ancient Athenians kept the Ship of Theseus in their harbor as a monument. Over the years, rotting planks were replaced with new wood. Eventually every single original plank had been swapped out. The philosophers of Athens asked: is it still the same ship?

Thomas Hobbes made it worse. Suppose someone collected all the removed planks and built a second ship from the originals. Now you have two ships. Which one is the "real" Ship of Theseus: the gradually restored ship, or the one built from the original materials?