MemoryDrawing bug fix for Issue #92

src/PhpSpreadsheet/Worksheet.php

@@ -2,6 +2,8 @@
 
 namespace PhpOffice\PhpSpreadsheet;
 
+use ArrayObject;
+
 /**
  * Copyright (c) 2006 - 2016 PhpSpreadsheet.
  *
@@ -2975,7 +2977,12 @@ public function __clone()
                     $newCollection->copyCellCollection($this);
                     $this->cellCollection = $newCollection;
                 } elseif ($key == 'drawingCollection') {
-                    $newCollection = clone $this->drawingCollection;
+                    $newCollection = new ArrayObject();
+                    foreach ($this->drawingCollection as $id => $item) {
+                        if (is_object($item)) {
+                            $newCollection[$id] = clone $this->drawingCollection[$id];
+                        }
+                    }
                     $this->drawingCollection = $newCollection;
                 } elseif (($key == 'autoFilter') && ($this->autoFilter instanceof Worksheet\AutoFilter)) {
                     $newAutoFilter = clone $this->autoFilter;

src/PhpSpreadsheet/Worksheet/MemoryDrawing.php

@@ -197,7 +197,7 @@ public function __clone()
         $vars = get_object_vars($this);
         foreach ($vars as $key => $value) {
             if (is_object($value)) {
-                $this->$key = clone $value;
+                $this->$key = unserialize(serialize($value));
             } else {
                 $this->$key = $value;
             }