$args = array(
'post_type' => 'page',
'posts_per_page' => -1,
'post_parent' => $post->ID,
);
$children= new WP_Query( $args );
$seasonepisode = array(
'post_title' => $episodetitle,
'post_content' => 'Some Content',
'post_status' => 'publish',
'post_parent' => $post->ID,
'post_type' => 'page',
'page_template' => 'template-songlist.php'
);
if ( $children->have_posts() ){
while ( $children->have_posts() ) {
$children->the_post();
if(get_the_title() != $episodetitle){
wp_insert_post($seasonepisode);
exit;
}
}//end of while
}else{wp_insert_post($seasonepisode);}//end have posts
wp_reset_postdata();
Alternatively
$query = new WP_Query();
$all_wp_pages = $query->query(array('post_type' => 'page'));
//$assuimg $post is current page
$children = get_page_children( $post->ID, $all_wp_pages );
$flag=true;
foreach($children as $child){
if($episodetitle == get_the_title($child))
$flag=false;
}
if($flag){
wp_insert_post($seasonepisode);
}