diff --git a/erpnext/selling/doctype/quotation/quotation.py b/erpnext/selling/doctype/quotation/quotation.py
index 84c4da1..eb04529 100644
--- a/erpnext/selling/doctype/quotation/quotation.py
+++ b/erpnext/selling/doctype/quotation/quotation.py
@@ -139,7 +139,7 @@
         msgprint("Item %s has been entered twice." % d.item_code)
         raise Exception
       else:
-        chk_dupl_itm.append(f)
+        chk_dupl_itm.append([cstr(d.item_code),cstr(d.description)])
 
 
   #do not allow sales item in maintenance quotation and service item in sales quotation