"Amethyst" is the exact same track as "Pendulum" on the first mini album. I wonder what's the deal about it. Purpose? Mistake?
EDIT: Well, after messaging CDJapan about the issue, they told me that it was indeed a production mistake. Shortly after my inquiry, the official site was updated with new information on the matter and
how to get a proper copy, too.
I'm lucky since CDJapan offered me to take care of the matter. I just had to send them my disc. (and they even reimbursed the postal fees with points!)