The easiest way to expose second accounts would to be publish the IP the post has come from. It won't catch all - e.g. working for an ISP I can give myself numerous IPs and some IPs will really have multiple users - i.e. those that work for the same company and post from work. In general though...
As you imply, it's not his friend - here's a post from the OP on Tuesday - an agenda me thinks :
"RDZ, A lettuce or Truss
Which is going to last the longest?"