Default post tab showing twice in admin bar

you may try to de-register/unset default post type and register post type with your requirements.

if ( ! function_exists( 'unset_default_post' ) ) :
function unset_default_post( ) {
    global $wp_post_types;
    $post_type="post";
    if ( isset( $wp_post_types[ $post_type ] ) ) {
        unset( $wp_post_types[ $post_type ] );
        return true;
    }
    return false;
}
endif;