I think that the following six accounts (all of them unregistered) belong to the same user: one, two, three, four, five, six. I base this judgement on the similarity of the usernames and gravatars, as well as the similar writing styles.
In this question (now deleted), I had left a comment requesting the user to confirm that all the accounts belong to them, and asking them not to create a different account for each new post. My comment got multiple upvotes, but no response from the OP; I do not know what more to do.
Can the moderators do something about this? Can the user be contacted and asked to stop this behavior?