diff --git a/classes/order/Order.php b/classes/order/Order.php
index b476cb371..6d624e8cc 100644
--- a/classes/order/Order.php
+++ b/classes/order/Order.php
@@ -1146,13 +1146,14 @@ class OrderCore extends ObjectModel
 			if ($use_existing_payment)
 			{
 				$id_order_payments = Db::getInstance()->executeS('
-					SELECT op.id_order_payment 
+					SELECT DISTINCT op.id_order_payment 
 					FROM `'._DB_PREFIX_.'order_payment` op
 					INNER JOIN `'._DB_PREFIX_.'orders` o ON (o.reference = op.order_reference)
 					LEFT JOIN `'._DB_PREFIX_.'order_invoice_payment` oip ON (oip.id_order_payment = op.id_order_payment)					
-					WHERE oip.id_order_payment IS NULL AND o.id_order = '.(int)$order_invoice->id_order);
-				
+					WHERE (oip.id_order != '.(int)$order_invoice->id_order.' OR oip.id_order IS NULL) AND o.id_order = '.(int)$order_invoice->id_order);
+
 				if (count($id_order_payments))
+				{
 					foreach ($id_order_payments as $order_payment)
 						Db::getInstance()->execute('
 							INSERT INTO `'._DB_PREFIX_.'order_invoice_payment`
@@ -1160,6 +1161,9 @@ class OrderCore extends ObjectModel
 								`id_order_invoice` = '.(int)$order_invoice->id.',
 								`id_order_payment` = '.(int)$order_payment['id_order_payment'].',
 								`id_order` = '.(int)$order_invoice->id_order);
+					// Clear cache
+					Cache::clean('order_invoice_paid_*');
+				}
 			}
 
 			// Update order cart rule
@@ -1465,6 +1469,9 @@ class OrderCore extends ObjectModel
 			$res = Db::getInstance()->execute('
 			INSERT INTO `'._DB_PREFIX_.'order_invoice_payment`
 			VALUES('.(int)$order_invoice->id.', '.(int)$order_payment->id.', '.(int)$this->id.')');
+
+			// Clear cache
+			Cache::clean('order_invoice_paid_*');
 		}
 		
 		return $res;
diff --git a/classes/order/OrderInvoice.php b/classes/order/OrderInvoice.php
index 2ab0cdf47..31614f2c5 100644
--- a/classes/order/OrderInvoice.php
+++ b/classes/order/OrderInvoice.php
@@ -522,14 +522,16 @@ class OrderInvoiceCore extends ObjectModel
 	 */
 	public function getTotalPaid()
 	{
-		if (!array_key_exists($this->id, self::$_total_paid_cache))
+		$cache_id = 'order_invoice_paid_'.(int)$this->id;
+		if (!Cache::isStored($cache_id))
 		{
-			self::$_total_paid_cache[$this->id] = 0;
+			$amount = 0;
 			$payments = OrderPayment::getByInvoiceId($this->id);
 			foreach ($payments as $payment)
-				self::$_total_paid_cache[$this->id] += $payment->amount;
+				$amount += $payment->amount;
+			Cache::store($cache_id, $amount);
 		}
-		return self::$_total_paid_cache[$this->id];
+		return Cache::retrieve($cache_id);
 	}
 
 	/**