The same thing happened to me. I e-mailed tech support to find out about a refund or getting Adrift for free. They said once my account was processed for the purchase, it would be credited (4-5 business days).
They did not say anything about how to purchase Adrift but, now that they are aware of the problem, I assume they will be addressing it so the proper download is attached to the Adrift link.
If you haven't already, contact tech support so you can be credited for the mistaken Doppelganger download.