How to Duplicate (multiple meta box)?

You didn’t add the save meta action for the facebook meta box.

<?php
/* Fire our meta box setup function on the post editor screen. */
add_action( 'load-post.php', 'sw_post_meta_boxes_setup' );
add_action( 'load-post-new.php', 'sw_post_meta_boxes_setup' );

/* Meta box setup function. */
function sw_post_meta_boxes_setup() {

  /* Add meta boxes on the 'add_meta_boxes' hook. */
  add_action( 'add_meta_boxes', 'sw_add_post_meta_boxes' );

  /* Save post meta on the 'save_post' hook. */
  add_action( 'save_post', 'sw_save_video_box_meta', 10, 2);
  add_action( 'save_post', 'sw_save_face_box_meta', 10, 2);

}

/* Create one or more meta boxes to be displayed on the post editor screen. */
function sw_add_post_meta_boxes() {

  add_meta_box(
    'sw_video_player',      // Unique ID
    esc_html__( 'Video Box', 'video-text' ),    // Title
    'sw_video_box_meta_box',   // Callback function
    'job_listing',// Admin page (custom post type)
    'normal',       // Context
    'high'          // Priority
  );

    add_meta_box(
    'sw_face_player',      // Unique ID
    esc_html__( 'Facebook Event Box', 'video-text' ),    // Title
    'sw_face_box_meta_box',   // Callback function
    'job_listing',// Admin page (custom post type)
    'normal',       // Context
    'high'          // Priority
  );


}

/* Display the post meta box. */
if ( !function_exists( 'sw_video_box_meta_box' ) ) {
function sw_video_box_meta_box( $object, $box ) { ?>

  <?php wp_nonce_field( basename( __FILE__ ), 'sw_video_box_nonce' ); ?>

  <p>
    <label for="sw_video_player"><?php _e( "Place Video/Playlist Embed Code Here.", 'sw-text' ); ?></label>
    <br />
    <textarea class="widefat" name="sw_video_player" id="sw_video_player" cols="50" rows="5"><?php echo esc_html__( get_post_meta( $object->ID, 'sw_video_box', true ) ); ?></textarea>
  </p>

<?php }

// Facebook Meta Box
if ( !function_exists( 'sw_face_box_meta_box' ) ) {
function sw_face_box_meta_box( $object, $box ) { ?>

  <?php wp_nonce_field( basename( __FILE__ ), 'sw_face_box_nonce' ); ?>

  <p>
    <label for="sw_face_player"><?php _e( "Place FB Video/Playlist Embed Code Here.", 'sw-text' ); ?></label>
    <br />
    <textarea class="widefat" name="sw_face_player" id="sw_face_player" cols="50" rows="5"><?php echo esc_html__( get_post_meta( $object->ID, 'sw_face_box', true ) ); ?></textarea>
  </p>

<?php }

    }
}


/* Save the meta box's post metadata. */
if ( !function_exists( 'sw_save_video_box_meta' ) ) {
function sw_save_video_box_meta( $post_id, $post ) {

  /* Verify the nonce before proceeding. */
  if ( !isset( $_POST['sw_video_box_nonce'] ) || !wp_verify_nonce( $_POST['sw_video_box_nonce'], basename( __FILE__ ) ) )
    return $post_id;

  /* Get the post type object. */
  $post_type = get_post_type_object( $post->post_type );

  /* Check if the current user has permission to edit the post. */
  if ( !current_user_can( $post_type->cap->edit_post, $post_id ) )
    return $post_id;

  /* Get the posted data and sanitize it for use as an HTML class. */
  $new_meta_value = ( isset( $_POST['sw_video_player'] ) ? balanceTags( $_POST['sw_video_player'] ) : '' );

  /* Get the meta key. */
  $meta_key = 'sw_video_box';

  /* Get the meta value of the custom field key. */
  $meta_value = get_post_meta( $post_id, $meta_key, true );

  /* If a new meta value was added and there was no previous value, add it. */
  if ( $new_meta_value && '' == $meta_value )
    add_post_meta( $post_id, $meta_key, $new_meta_value, true );

  /* If the new meta value does not match the old value, update it. */
  elseif ( $new_meta_value && $new_meta_value != $meta_value )
    update_post_meta( $post_id, $meta_key, $new_meta_value );

  /* If there is no new meta value but an old value exists, delete it. */
  elseif ( '' == $new_meta_value && $meta_value )
    delete_post_meta( $post_id, $meta_key, $meta_value );
    } 
}

/* Save the meta box's post metadata. Facebook Box */
if ( !function_exists( 'sw_save_face_box_meta' ) ) {
function sw_save_face_box_meta( $post_id, $post ) {

  /* Verify the nonce before proceeding. */
  if ( !isset( $_POST['sw_face_box_nonce'] ) || !wp_verify_nonce( $_POST['sw_face_box_nonce'], basename( __FILE__ ) ) )
    return $post_id;

  /* Get the post type object. */
  $post_type = get_post_type_object( $post->post_type );

  /* Check if the current user has permission to edit the post. */
  if ( !current_user_can( $post_type->cap->edit_post, $post_id ) )
    return $post_id;

  /* Get the posted data and sanitize it for use as an HTML class. */
  $new_meta_value = ( isset( $_POST['sw_face_player'] ) ? balanceTags( $_POST['sw_face_player'] ) : '' );

  /* Get the meta key. */
  $meta_key = 'sw_face_box';

  /* Get the meta value of the custom field key. */
  $meta_value = get_post_meta( $post_id, $meta_key, true );

  /* If a new meta value was added and there was no previous value, add it. */
  if ( $new_meta_value && '' == $meta_value )
    add_post_meta( $post_id, $meta_key, $new_meta_value, true );

  /* If the new meta value does not match the old value, update it. */
  elseif ( $new_meta_value && $new_meta_value != $meta_value )
    update_post_meta( $post_id, $meta_key, $new_meta_value );

  /* If there is no new meta value but an old value exists, delete it. */
  elseif ( '' == $new_meta_value && $meta_value )
    delete_post_meta( $post_id, $meta_key, $meta_value );
    } 
}