WordPress page numbers with Yoast SEO plugin. Add to functions.php. This will add " - Page x" to titles and meta descriptions in paginated archives (categories, blog post archives).Based on http://www.htpcbeginner.com/resources/codes/page-number-meta-description.txt

add_page_numbers.php

<?php 

//Add page number to Yoast meta description and page titles to avoid duplication (when using customised titles/descriptions)
if ( ! function_exists( 'cvw_add_page_number' ) )
{
    function cvw_add_page_number( $s )
    {
        global $page;
        $paged = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
        ! empty ( $page ) && 1 < $page && $paged = $page;

        $paged > 1 && $s .= ' - ' . sprintf( __( 'Page %s' ), $paged );

        return $s;
    }
    
    add_filter( 'wpseo_metadesc', 'cvw_add_page_number', 100, 1 );
    add_filter( 'wpseo_title', 'cvw_add_page_number', 100, 1 );
}