Seems like this type of scamming practice is increasing these days. We have just seen a similar scam attempt via a poll, and you are aware of it as well. I think I have seen a thread before where the newbie guy asks some questions, and later they reply to that thread using their alternative account so they can get merits. It seems such tricks are working for them, which is why similar cases keep appearing.
Bitlist.co does that, but it's far from perfect since Bitcointalk doesn't provide API to return list of recently edited post/thread. They managed to caught 3 of 5 edit by those user, see
This was a nice addition. However, I didn't know that it does not always work. Any idea why the other two didn't worked?