In block_myoverview, we can choose a custom field to enable filtering by, but this does not work if there is an existing custom field (not a course field) with the same shortname.

To reproduce:

• Go to /question/bank/customfields/customfield.php and create a field with shortname "test"
• Go to /course/customfield.php and create a field with shortname "test"
• Go to /admin/settings.php?section=blocksettingmyoverview, tick the "Custom field" box and set the "Field to use" to the course custom field just created
• Create a course and set the custom field just created to "TEST"
• Add the "Course overview" to your dashboard
• You will see an error message "Error: mdb->get_record() found more than one record!" (if debug display is on) and the course field value added does not appear in the filter list. Expected behaviour is that "TEST" appears in the filter list.
• Delete the question custom field created in the first step and refresh the dashboard page. "TEST" now appears in the list as expected.