Did you visit my site? 
I see what you mean, when I search the in the GUI, I do see two. However, when I click on both as an admin and bring up the details page, they appear to be the same user. I can’t find a single detail that’s different between the two. Basically, no matter which one of those I click, I get the data for the second one, the one with the full name entered.
Since that user had never posted, and not visited in a while, I deleted the account from the GUI.
Interestingly, I still have the other one, the first one on your list, without a full name. But now, if I click on that user, nothing happens. I can see a dialog trying to open, then immediately closing.
Searching the database directly for username = DaveW now returns zero rows. However, if I search for
select * from users WHERE name = 'DaveW';
(name, not username,) I get 1 row returned:
19732 | DaveW | 2016-11-15 12:43:02.708166 | 2016-11-15 12:43:02.708166 | DaveW | 0 | | | | t | davew | 2016-11-15 12:43:02.708166 | f | 2017-06-01 18:09:45.018058 | 1 | f | | | | | | | 0 | 0 | | f | | | | | | f | | | | |
(1 row)
Notice how it has DaveW (same spelling) in the username field! This account is also three years older than the other one.
Can I get rid of it with:
DELETE from users WHERE id = 19732;
without any ill effects?
Thanks for all your help!
Gunnar