Problem adding sidebar to Underscores theme

I have been struggling with this for hours now, any help appreciated. I am using Underscores theme with one sidebar (sidebar-1, on the left) and Custom Sidebars plugin so that I can have different side content on each page. The problem is when I add a new sidebar (sidebar-2) which I want to appear just above the footer to contain the same content on every page.

functions.php:

function myunderscores3_widgets_init() {
    register_sidebar( array(
        'name'          => esc_html__( 'Sidebar', 'myunderscores3' ),
        'id'            => 'sidebar-1',
        'description'   => esc_html__( 'Add widgets here.', 'myunderscores3' ),
        'before_widget' => '<section id="%1$s" class="widget %2$s">',
        'after_widget'  => '</section>',
        'before_title'  => '<h2 class="widget-title">',
        'after_title'   => '</h2>',
        //'before_title' => '<!--', 
        //'after_title' => '-->',       
    ) );
    register_sidebar( array(
        'name'          => esc_html__( 'Bottom Sidebar', 'myunderscores3' ),
        'id'            => 'sidebar-2',
        'description'   => esc_html__( 'Add widgets here.', 'myunderscores3' ),
        'before_widget' => '<section id="%1$s" class="widget %2$s">',
        'after_widget'  => '</section>',
        'before_title'  => '<h2 class="widget-title">',
        'after_title'   => '</h2>',
        //'before_title' => '<!--', 
        //'after_title' => '-->',       
    ) );
}
add_action( 'widgets_init', 'myunderscores3_widgets_init' );

sidebar.php (for the sidebar-1 content):

if ( ! is_active_sidebar( 'sidebar-1' ) ) {
    return;
}
?>

<aside id="secondary" class="widget-area">
    <?php dynamic_sidebar( 'sidebar-1' ); ?>
</aside><!-- #secondary -->

page.php (to pull in sidebar-1):

<?php
get_sidebar();
?>
</div><!-- wrapper -->    
footer.php (to pull in sidebar-2):

if (is_active_sidebar( 'sidebar-2' )) {
      dynamic_sidebar( 'sidebar-2' );
  }
?>
    </div><!-- #content -->

After adding widget content to sidebar-2 this is working fine on every page apart from the one page that has no sidebar-1 content. On this page the sidebar-2 content is appearing twice – on the bottom as expected and in sidebar-1 content area also ! Furthermore the ‘no-sidebar’ class is missing from the body. In the backend the sidebar-1 widgets are located through each individual page whereas the sidebar-2 content is located through the widget (‘As Sidebar for selected Post Types’ – Pages). On the actual page where the sidebar-2 content is appearing twice I have not specified any sidebars inside the actual page as I am doing this through the widget settings. Any ideas ? Thank you

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