Index: __init__.py
===================================================================
--- __init__.py	(revision 4085)
+++ __init__.py	(working copy)
@@ -666,6 +666,9 @@
 
     def save_file(self, new_data, new_object, original_object, change, rel):
         FileField.save_file(self, new_data, new_object, original_object, change, rel)
+        upload_field_name = self.get_manipulator_field_names('')[0]
+        if new_data.get(upload_field_name, False) and change:
+            self.delete_file(original_object) # delete original file
         # If the image has height and/or width field(s) and they haven't
         # changed, set the width and/or height field(s) back to their original
         # values.