The following bug has been logged on the website:
Bug reference:      9050
Logged by:          Alexey Bashtanov
Email address:      bashtanov@imap.cc
PostgreSQL version: 9.3.1
Operating system:   Linux
Description:
hello!
such a query run under superuser produces non-empty result:
select userid, dbid, query from pg_stat_statements() group by 1,2,3 having
count(1) > 1;
I am not sure how to reproduce it, but it can be reproduced only on those
instances having several databases on it.
Regards, Alexey