Dual Accounts instead of one??

Apparently I now have two sub accounts for final fantasy under one account, I took my time and entered the code I got but instead of applying it to my current account it started up a second "tab" on my account, which basically split it in two with my pre order code "account" no longer being able to play and my "new" purchased account no longer having my characters on it.

What am I meant to do, this is mental. No other mmo game handles there accounts this way, it's just not normal. You have one account and every code you enter applies to that account, it doesn't suddenly decide to start up a second account for you.