The downloads listed in your Free Downloads log are downloads that occurred because of links sent manually using the "Send free download link" function in your Seller Admin. I think that also logs any links sent using the "Send Updates/Newsletter" function as well -- basically any links issued which were not sent as a result of a buyer taking a regular order to checkout.
If you are seeing downloads logged there when you know you did not send any free download links, then it sounds like someone hacked into your E-junkie account and issued some free links without your knowledge. If you did not have any difficulty logging in around that time, they may have guessed your E-junkie password somehow. If you couldn't log in around then and needed to reset your password, they may have actually guessed or hacked your Email account's password, so then they could receive the reset-password messages we send to your email address when using the Forgot Password function. It would be a very good idea to change your E-junkie and Email account passwords now.