Widget is displayed in two places

OK, I used just normal function and it’s ok.

function twentytwentychild_widgets_init() {
    register_sidebar( array(
        'name'          => __( 'Widget name', 'twentytwentychild' ),
        'id'            => 'after-post',
        'description'   => __( 'Widget desc.', 'twentytwentychild' ),
        'before_widget' => '',
        'after_widget'  => '',
        'before_title'  => '',
        'after_title'   => '',
    ) );
}
add_action( 'widgets_init', 'twentytwentychild_widgets_init' );