Two websites using CI conflict, caused by session?

Hello. 
I just realize this, i curently working on 2 website using CI, and it looks similar because the second comes from the first one with modification client needs. All is all okey. But when i open in the same time, the website become strange , for example error php, or menu from web A is shown on web B, web A logout then the  web B become logout too. It happen in localhost and real server internet.  But when i open that two website in two different browser, it normal and doesn't act strange.

I googling and it says maybe from session conflict. Is it correct? And any ideas to solve the problem? Thanks.

Change your login cookie name. They can't have the same name, as both will load it.

Yes, i try diferenciate that two website.
In config/config.php

$config['sess_cookie_name'] = 'ci_session_websiteA';
$config['sess_cookie_name'] = 'ci_session_websiteB';

And i think it works well now, thanks