PG Bug reporting form <noreply@postgresql.org> writes:
> We have a table with a primary key of type String, we noticed that we have
> more than one row with the same primary key.
Most likely this happened because the primary key index became corrupt
due to a change in the underlying system's sort ordering. This page
has some info about that type of problem:
https://wiki.postgresql.org/wiki/Locale_data_changes
regards, tom lane
