MAGETWO-69289: The "extra_customer_info" container duplicates in template

- Exclude container from output

Author: isxam

app/code/Magento/Sales/Block/Adminhtml/Order/View/Info.php

@@ -303,4 +303,26 @@ public function getFormattedAddress(Address $address)
     {
         return $this->addressRenderer->format($address, 'html');
     }
+
+    /**
+     * @inheritdoc
+     */
+    public function getChildHtml($alias = '', $useCache = true)
+    {
+        $layout = $this->getLayout();
+
+        if ($alias || !$layout) {
+            return parent::getChildHtml($alias, $useCache);
+        }
+
+        $childNames = $layout->getChildNames($this->getNameInLayout());
+        $outputChildNames = array_diff($childNames, ['extra_customer_info']);
+
+        $out = '';
+        foreach ($outputChildNames as $childName) {
+            $out .= $layout->renderElement($childName, $useCache);
+        }
+
+        return $out;
+    }
 }