Now it's become quite complicated to judge connected accounts only based on transaction history. They probably sell each other or there is someone reselling. We assume they are connected but who knows the real story. It wouldn't be prohibited dealing with each other out of the forum even they use a forum account. But if there is some other link with each other like a social account or uses the same address then a red tag would be appropriate. I think coinlocket$'s neutral feedback is fine in that case.