SELECT o.customer_id
#      , GROUP_CONCAT(DISTINCT o.id) AS orders
#      , COUNT(DISTINCT REPLACE(TRIM(r.card), ' ', '')) AS q
     , SUBSTRING_INDEX(GROUP_CONCAT(DISTINCT REPLACE(TRIM(r.card), ' ', '') ORDER BY date_paidoff DESC), ',', 1) AS cards
FROM yii_doc.refund r
LEFT JOIN yii_doc.orders o ON o.id = r.order_id
WHERE o.id IS NOT NULL
  AND r.card <> ''
  AND r.card IS NOT NULL
GROUP BY o.customer_id
# HAVING q > 1;