Fixed a bug, that when a second header was added to a section, all

images added to the second header were assigned to the first header,
resulting in at least a corrupted DOCX.

Author: Bas-Jan 't Jong

src/PhpWord/Element/AbstractContainer.php

@@ -355,7 +355,7 @@ private function checkElementDocPart()
         $docPart = $isCellTextrun ? $this->getDocPart() : $this->container;
         $docPartId = $isCellTextrun ? $this->getDocPartId() : $this->sectionId;
         $inHeaderFooter = ($docPart == 'header' || $docPart == 'footer');
-
+        $docPartId = $inHeaderFooter ? $this->getDocPartId() : $docPartId;
         return $inHeaderFooter ? $docPart . $docPartId : $docPart;
     }