Keep the custom permalinks unique

function pm_unique_permalinks($default_uri, $native_slug, $element, $post_name, $native_uri) {
    global $permalink_manager_uris;

    // Ignore native permalinks
    if($native_uri) { return $default_uri; }

    // Store all the custom permalinks in a separate variable
    $uris = $permalink_manager_uris;

    // Exclude this element
    if(!empty($element->ID) && !empty($uris[$element->ID])) {
        unset($uris[$element->ID]);
    } else if(!empty($element->term_id) && !empty($uris[$element->term_id])) {
        unset($uris["tax-{$element->term_id}"]);
    }

    do {
        $duplicates_ids = array_keys($uris, $default_uri);
        $duplicates_ids_count = count($duplicates_ids);

        if(!empty($duplicates_ids_count)) {
            preg_match('/(.+?)(?:-([\d]+))?(\.[^\.]+$|$)/', $default_uri, $parts);
            $index = (!empty($parts[2])) ? $parts[2] + 1 : 2;

            $default_uri = preg_replace('/(.+?)(?:-([\d]+))?(\.[^\.]+$|$)/', '$1-' . $index . '$3', $default_uri);
        }
    } while ($duplicates_ids_count > 0);

    return $default_uri;
}
add_filter('permalink_manager_filter_default_post_uri', 'pm_unique_permalinks', 999, 5);
add_filter('permalink_manager_filter_default_term_uri', 'pm_unique_permalinks', 999, 5);