diff --git a/tools/post_process_props.py b/tools/post_process_props.py
index 78a23fb..d8c9cb1 100755
--- a/tools/post_process_props.py
+++ b/tools/post_process_props.py
@@ -88,6 +88,8 @@
     if len(overriding_props) > 1:
       # duplicated props are allowed when the all have the same value
       if all(overriding_props[0].value == p.value for p in overriding_props):
+        for p in optional_props:
+          p.delete("overridden by %s" % str(overriding_props[0]))
         continue
       # or if dup is explicitly allowed for compat reason
       if allow_dup: