There are times when one person has a number of accounts. The term is “Dual”.
In ancient days, we would join sites as ourselves, from Jamaica. We would receive second class treatment. So we would join the same site, using an American proxy.
There were sites which allowed you to log on, then use that site to join other sites.
We joined as ourselves, then as an American so that we would be treated fairly.
Today, many people use them for nefarious purposes.
One person may object to an opinion and create a number of accounts so that it will seem a dozen different people object.
Trolls often have five or six accounts on a site.
Other uses is when the owner of a site create a user account so to be, ‘just like you’.
In some cases, it is done to pull your tongue, (getting you to say something that can and will be used against you), in some to simply get a ground zero impression of the site and its members.
When a member ‘just like you’, begins to post about the site, it is pretty clear that this is not a member, this is someone who knows more than you about the site.
The best thing is to stay away from that user.