SELECT a.*, CONCAT_WS(' - ', a.uid_genexis_products, p.name) as name1, CONCAT_WS(' - ' , uid_genexis_products_add, p2.name) AS name2 FROM genexis_add_to_order a 
LEFT JOIN genexis_products p ON p.uid = a.uid_genexis_products 
LEFT JOIN genexis_products p2 ON p2.uid = a.uid_genexis_products_add