About not having to pay 50 for the second name, possibly the system detected that it took your NC by mistake when you tried to get d/q ?
Hehe. Well, I couldn't get the second either. I'm guessing it was already in name_scan and I didn't see it, that's why it didn't give me an error. d/q wasn't when I tried to update (though I'm not sure). It could as well be the other way around. (It must be the other way around, since you also got the same behavior, but it makes less sense IMO.)
Yep, I had the exact same thing happen to me when I tried to register d/q. I lost 50 NC and got the same error.
I'm hoping there was a fork of some sorts and we'll get back our NCs when the network gets rid of it. We need a block explorer, quick!

Have you tried restarting with namecoind -rescan?