In the past 12 moths there are 7695 exchanges in total. Only 24 of them are negative exchanges (1 or 2 stars) reprezenting 0.31% of the total exchanges.
Those two accounts belong to the same person. One of the accounts is blocked and the other one is limited. If this account receives another negative rating, it will be blocked as well.
The ratings you give decides if an account is limited or blocked. I think that the message you sent to this member is clear. I also sent a message to encourage him to increase the quality of his exchanges.