You can try this. However, I am sure there must be a better alternative..
$past_events = get_posts(array(
'post_type' => Tribe__Events__Main::POSTTYPE,
'paged' => $paged,
'posts_per_page' => '10',
'eventDisplay'=>'past',
'orderby'=> 'title',
'order' => 'ASC',
's' => $searchText ?: '',
));
$post_arr = array();
foreach ( $past_events as $past_event ) {
$post_arr[ $past_event->post_title ] = $past_event->ID;
}
$post_arr
will now contain the title of the latest post containing same title as key and the post id as value.