Create more than one section in Theme Customizer

The hook customize_register is for include all your custom settings to the default core settings. Your code is a good start, Hook, there init a function, there include all settings, and sections. But you register 2 section areas with the same ID; there is wrong. If you will create two different sections on the customizer, then create also two different key, IDs for the sections – $wp_customize->add_section.
A exmaple:

    // Set option key based on get_stylesheet()
    $this->theme_key  = $args['theme_key'];
    $this->option_key = $this->theme_key . '_theme_options';

    // ===== Layout Section =====
    // Option for leave sidebar left or right
    $wp_customize->add_section( $this->option_key . '_layout', array(
        'title'       => __( 'Layout', 'documentation' ),
        'description' => __( 'Define main Layout', 'documentation' ),
        'priority'    => 30
    ) );

    // ===== Custom Section =====
    // create custom section for rewrite url
    $wp_customize->add_section( $this->option_key . '_rewrite_url', array(
        'title'       => __( 'Rewrite', 'documentation' ),
        'priority'    => 35,
    ) );

You can create many sections, how yoo want and register also different options per section. Maybe you see on this example for a ready usable solution:

• Theme Documentation
• Tutorial
• Classes, there enhance the default core customizer