I didn't actually place the second order, but it's shown as "activated" (and reflects the discount) in my shopping cart.

You very well were not actually "logged in". You may have thought you were but in reality you were not. I had the same thing happen to me, and when I hit "checkout" it prompted me to log-in even though I thought I was and then tell me this account has already used this code.

I've had two items cancelled and they refunded the shipping too. Sucks, because I wanted those items, but it made the rest of the order that much better of a deal (especially as one of them was the full priced shipping cost of a group of books from one store).

Seven books for $60, free shipping, saved $25! Many thanks to Jaymole! This was all stuff I had in my Amazon cart for weeks and could never find a good deal that the extra four bucks shipping didn't kill.

Code still worked today (5/30). Saved $15.45 in shipping fees. Thanks OP!!!

Made 3 separate orders, saving about $35 shipping. Excellent find!

Did you use separate accounts?