Cron.php no longer completes successfully on my Moodle site. It reaches the step labeled "Starting the completion cron...", hangs for a few seconds, and then prints "Found more than one record in fetch() !" and aborts.
I had had received a similar error (however just within a course) when I dupicated activites in a course with activity completion active. As soon as I deleted all of the duplicated activities, I was able to view activity completion options again without the error. I have also duplicated courses with activity completion enabled and set-up and am now seeing an error of the same name in the cron.php script info. I have deleted the course which was duplicated, but the error persists. This sounds like a large bug; I am wondering if anyone has experienced this and/or is familiar with the issue. Running health.php returns no problem found. Moodle 2.1.1 is the version.