Duplicate session id error in database table

Duplicate issue is still happening. We've had 2 new cases so far.

Code:

ERROR - 2017-07-23 00:17:12 --> Query error: Duplicate entry 'aq64m773luqkia96p1h3lniaj1e4ngg6' for key 'PRIMARY' - Invalid query: INSERT INTO `db_session` (`id`, `ip_address`, `timestamp`, `data`) VALUES ('aq64m773luqkia96p1h3lniaj1e4ngg6', '162.158.138.38', 1500740232, '__ci_last_regenerate|i:1500739999;[other_data];')
ERROR - 2017-07-23 00:17:12 --> Severity: Warning --> Unknown: Failed to write session data (user). Please verify that the current setting of session.save_path is correct (db_session) Unknown 0
ERROR - 2017-07-23 00:21:11 --> 404 Page Not Found: Public/img
ERROR - 2017-07-23 00:23:14 --> 404 Page Not Found: Apple-touch-icon-120x120-precomposedpng/index
ERROR - 2017-07-23 00:25:38 --> 404 Page Not Found: Wp-loginphp/index
ERROR - 2017-07-23 00:27:09 --> Query error: Duplicate entry '42de1o9h22dfsbftlgsvmn7ake17p2br' for key 'PRIMARY' - Invalid query: INSERT INTO `db_session` (`id`, `ip_address`, `timestamp`, `data`) VALUES ('42de1o9h22dfsbftlgsvmn7ake17p2br', '162.158.138.44', 1500740829, '__ci_last_regenerate|i:1500740671;[other_data];')
ERROR - 2017-07-23 00:27:09 --> Severity: Warning --> Unknown: Failed to write session data (user). Please verify that the current setting of session.save_path is correct (db_session) Unknown 0