From my comment on MDL-49065

I am getting the following notices when I login as a student

{{Did you remember to make the first column something unique in your call to get_records? Duplicate value '6' found in column 'id'.

line 791 of /lib/dml/pgsql_native_moodle_database.php: call to debugging()
line 454 of /mod/lesson/lib.php: call to pgsql_native_moodle_database->get_records_sql()
line 47 of /blocks/course_overview/locallib.php: call to lesson_print_overview()
line 75 of /blocks/course_overview/block_course_overview.php: call to block_course_overview_get_overviews()
line 288 of /blocks/moodleblock.class.php: call to block_course_overview->get_content()
line 230 of /blocks/moodleblock.class.php: call to block_base->formatted_contents()
line 971 of /lib/blocklib.php: call to block_base->get_content_for_output()
line 1023 of /lib/blocklib.php: call to block_manager->create_block_contents()
line 473 of /lib/outputrenderers.php: call to block_manager->ensure_content_created()
line 52 of /theme/clean/layout/columns3.php: call to core_renderer->standard_head_html()
line 1015 of /lib/outputrenderers.php: call to include()
line 945 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line 165 of /my/index.php: call to core_renderer->header()

Did you remember to make the first column something unique in your call to get_records? Duplicate value '5' found in column 'id'.

line 791 of /lib/dml/pgsql_native_moodle_database.php: call to debugging()
line 454 of /mod/lesson/lib.php: call to pgsql_native_moodle_database->get_records_sql()
line 47 of /blocks/course_overview/locallib.php: call to lesson_print_overview()
line 75 of /blocks/course_overview/block_course_overview.php: call to block_course_overview_get_overviews()
line 288 of /blocks/moodleblock.class.php: call to block_course_overview->get_content()
line 230 of /blocks/moodleblock.class.php: call to block_base->formatted_contents()
line 971 of /lib/blocklib.php: call to block_base->get_content_for_output()
line 1023 of /lib/blocklib.php: call to block_manager->create_block_contents()
line 473 of /lib/outputrenderers.php: call to block_manager->ensure_content_created()
line 52 of /theme/clean/layout/columns3.php: call to core_renderer->standard_head_html()
line 1015 of /lib/outputrenderers.php: call to include()
line 945 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line 165 of /my/index.php: call to core_renderer->header()}}

I am not sure what exactly are the environment conditions that are triggering this, but this issue does seem to be the cause. Will wait for Stephen to respond before creating an issue.

Thanks