Looking at your account I think I know what happened. When you registered the Music Creation Suite, all the products are registered with it. (AudioBox USB, Studio One 3 and Notion 5). You do not have to type in the serial number for the AudioBox because it's already part of the bundle. If you do, you will get an error that the serial number is already registered or is invalid. So what a lot of people do instead of contacting support, is they create a second (or 3rd, or 4th, or 5th) my.presonus.com account thinking something went wrong only to get a similar error now saying, this product is already registered, not knowing it's already registered to themselves under a different email address.
The solution is very easy. Just login to your my.presonus.com account that you used to register your Music Creation Bundle and download, install and activate the software.
Follow this tutorial to access your software: http://support.presonus.com/entries/68214964-How-do-I-access-my-Studio-One-3-software-I-don-t-see-it-in-my-account-
Then continue with this tutorial: http://support.presonus.com/entries/68141864--3-Studio-One-3-Software-Activation-Online-Computer-
More will follow after that one and you'll be on your way.
Just so you (and others who may read this after you)
There is no way for PreSonus to automatically associate the different My PreSonus logins if you use a different email address when you create a new account. If you're not sure which account your products are registered in, the best thing to do is to STOP and contact presonus tech support at http://support.presonus.com
so we can get all your products into a single account that you can use to access and activate your products.