Well, ID’s and email addresses are often (always?) not duplicated ... names not so much since the world is full of duplicate names and to do that would very shortly (short term) be non functional.

Like I said, If you know the setting we are missing (since WordPress is used and used by millions), let us know.

—rms

No, you aren't ever going to run out of commenting names - they are just strings of characters (if you look at the forum, very few of the posting names are actual names. And if you think about it, yahoo never ran out of email addresses - if you tried to pick one that was already in use you were told to pick another one (usually they suggested one by adding as high a number as necessary to make it unique).

I used to post on forums, chats, Disqus etc regularly a few years back, and you were never allowed to use a name already in use.

It is what it is, though.

I recommend you go into your profile on the main site and edit your "Nickname" and your "Display Name Publicly As". All your old postings will be shown with the new setting.

You can change it to something just as anonymous as "Mark" again, or perhaps use your real name?

I know this works. I tested it with my own id and all old postings (few that they are) were updated with the adjusted new "Display Name Publicly As" setting.

All the above is fully in your control.

I also know there is no setting we can find that controls "Display Name Publicly As" to unique strings of text.

Regarding your assertions about identity and assumptions about unique display names, it appears you are mixing up *identity* which needs to be unique, of course with "Display Name Publicly As" and "Nicknames". Identity in WordPress is your UserID.

Your UserID, which is shown in your profile must be and is unique within the UserID space, and only if you chose to show your UserID publicaly as "Display Name Publicly As" will it be shown in postings. That is up to you. Also in WordPress your email address is unique since your UserID can't be validated unless you respond to the security challenge. Your "imposter" Mark (?) can't of course, I hope, get into your email account and respond on your behalf. Control of your email account and setting up your UserID is also fully in your control.

If the other "Mark" follows you with your new "Display Name Publicly As", then for sure we can conclude that he/she/whatever is doing nefarious things. We can block the IP that the postings are coming from, but residential IP addresses are mostly not fixed so it's not really totally effective against someone committed to mischief. We can delete the ID of course, but then he/she/whatever can simply get a new ID and change the "Display Name Publicly As" they use to what you use.

There is no federated identity system on the Internet. Yes, of course Google, Facebook, Discus, and so many others (including Governments) are trying and hoping to become that, but so far that has not happened.

I can't take this issue any further for you at this time.