Why does ci_sessions create two identical sessions?

Question

CodeIgniter

Codeigniter 3
Session Config

$config['sess_driver'] 				= 'database';
$config['sess_cookie_name'] 		= 'ci_session';
$config['sess_expiration'] 			= 0;
$config['sess_save_path'] 			= 'ci_sessions';
$config['sess_match_ip'] 			= FALSE;
$config['sess_time_to_update'] 		= 360;
$config['sess_regenerate_destroy'] 	= TRUE;
$config['sess_expire_on_close']	    = FALSE;
$config['sess_encrypt_cookie']	    = TRUE;
$config['sess_use_database']	    = TRUE;
$config['sess_table_name']		    = 'ci_sessions';

Yes, the config may look strange

For authorization, I use Ion_Auth
Sessions in the database are completely the same, only the id changes
One of them is used by the site and the second simply exists

Answer 1

the solution was the simplest
Comment out in ion_auth_model
$this->session->sess_regenerate(FALSE);
I still do not understand why it is needed, if you know, hurry up