I've had a bunch of alerts to completely empty registrations for my email list come up in the last week, so I went to my site to see what was going on.
Turns out, you can just click the "Register" button without filling in your name and email, and you get the download without subscribing. This happens whether a double opt-in is required or not.
I dunno...seems like a bad idea to me. See for yourself (just click to register and leave the input fields blank):