Comment 3 for bug 1744153

Here's a little something that you can run to see if you have user names in the database that differ only in case. We have a few hundred such duplicates, though a handful look like duplicate patrons who used the same user name, once in uppercase and once in lowercase.

select a.id, a.usrname, b.id, b.usrname
from actor.usr a
join actor.usr b
on lower(b.usrname) = lower(a.usrname)
and b.id > a.id
and not a.deleted and not b.deleted;