Fix comment typo.
diff --git a/Tools/scripts/gencodec.py b/Tools/scripts/gencodec.py
index 46563df..fdaa8fe 100644
--- a/Tools/scripts/gencodec.py
+++ b/Tools/scripts/gencodec.py
@@ -95,7 +95,7 @@
         else:
             enc2uni[enc] = (uni,comment)
     # If there are more identity-mapped entries than unmapped entries,
-    # it pays to generate an identity dictionary first, add add explicit
+    # it pays to generate an identity dictionary first, and add explicit
     # mappings to None for the rest
     if len(identity)>=len(unmapped):
         for enc in unmapped: