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I get many double user when update admin employer profile, How to solve this?

Remove double employer posts and solve your issue with this code

add_action('init', function(){
    $error_user_id = 1;
    $linked_employer_post_id = 1;
    //Find and remove all double user for error user
    $posts = get_posts(array(
        'post_type' => 'iwj_employer',
        'posts_per_page' => -1,
        'post_status' => 'iwj-incomplete',
        'author' => $error_user_id
    ));
    if(isset($_GET['dev'])){
        foreach($posts as $p){
            wp_delete_post($p->ID, true);
        }
    }
    //Fixed error
    update_user_meta($error_user_id, '_iwj_employer_post',$linked_employer_post_id);
});

Change your $error_user_id and and $linked_employer_post_id value by your value.

Add this code to file functions.php in theme folder then run site on url: yoursite.com/?dev

Remove code after your issue solved.