dedup_views.module

<?php
/**
 * @file
 * dedup_views functionality
 */

/**
  * @implements hook_views_pre_view().
  *
  * https://api.drupal.org/api/views/views.api.php/function/hook_views_pre_view/7
  */
function dedup_views_views_pre_view(&$view, &$display_id, &$args){
  // Uncomment if using Devel Module to find the name of the View & View Display
  // dpm($view);

  // View that is loaded in code to get NIDs for exclusion
  $featured_view_name = 'featured_news';
  $featured_view_display = 'block';
  // View that is being deduped
  $automated_view_name = 'automated_news';
  $automated_view_display = 'block';

  // Only modify the view we intend to
  if ($view->name == $automated_view_name && $display_id == $automated_view_display) {
    $node_ids = dedup_views_nids_for_exlusion($featured_view_name, $featured_view_display);

    // Pass in NIDs of manually referenced content for exlucsion (or de-duping)
    if (!empty($node_ids)) {
      // $args[] are Views Arguments for the Contextual Filter
      // A contectual filter must be added and configured to your view
      $args[] = $node_ids;
    }
  }
}

function dedup_views_nids_for_exlusion($view_name,$view_display) {
  $nids = array();
  $results = array();

  // Load the view
  // https://api.drupal.org/api/views/views.module/function/views_get_view/7
  $view = views_get_view($view_name);
  $view->set_display($view_display);
  $view->pre_execute();
  $view->execute();

  // Get the results
  $results = $view->result;

  // Make sure there is at least one result
  if (count($results) > 0) {
    // Build the final array of nids for exlusion
    foreach ($results as $result) {
      // The result nid may not always be in the same location
      // dpm($result) to help troubleshoot...Devel Module Required
      if (isset($result->nid)) {
        $nids[] = $result->nid;
      }
    }

    // Return $nids in a format we need (comma or plus seperated)
    // This is the same format the Views contextual filter would expect if
    // You manually typed in a list of NIDs
    return implode('+', $nids);
  }

}