Compruebe si la sesión se inicia PHP
if (session_status() == PHP_SESSION_NONE) {
session_start();
}
Friendly Hawk
if (session_status() == PHP_SESSION_NONE) {
session_start();
}<?php
if(session_status() == PHP_SESSION_ACTIVE){
//a session is already running
session_destroy(); //stops the session
}
?>