Anybody get multiple Chromecast's in the most recent Amazon promotion?

I bought a couple Chromecasts in Amazon's most recent promotion that gives you $6 in Google Play store credit. I just got an email with my promo code for this. I assumed I'd get $12 in credit for two Chromecasts, but I only got $6. Did anyone else order multiples in this promotion? Do you only get a single $6 credit per order (in which case I wish I had used two orders)?