Out of curiosity, I signed out, made a LOL and submitted it as Unknown. Giving one's name and information is a very clear option. So those showing as Unknown is a deliberate choice by the maker of the LOL.
ED'd part of yur conversation about close similarity between LOLz. I just had the experience with one I made where the capshun showed up, with only a slight variation, on someone else's (image was different) but the capshun, I am sure, was no coincidence.