diff --git a/core/modules/ckeditor/js/ckeditor.js b/core/modules/ckeditor/js/ckeditor.js
index 313621f..146fc6d 100644
--- a/core/modules/ckeditor/js/ckeditor.js
+++ b/core/modules/ckeditor/js/ckeditor.js
@@ -36,7 +36,14 @@
       var label = $('label[for=' + element.getAttribute('id') + ']').html();
       format.editorSettings.title = Drupal.t('Rich Text Editor, !label field', {'!label': label});
 
-      return !!CKEDITOR.replace(element, format.editorSettings);
+      // When the Drupal Attach Behaviours are executed after the CKeditor
+      // instances have been initialized, we have to prevent initializing a
+      // new CKeditor instance if there already exists one for this text field.
+      // This might happen e.g. during rearrangement of multiple field items
+      // containing CKeditor instances.
+      if (!CKEDITOR.instances[element.getAttribute('id')]) {
+        return !!CKEDITOR.replace(element, format.editorSettings);
+      }
     },
 
     /**