Fix duplicate word.
diff --git a/Doc/library/htmlparser.rst b/Doc/library/htmlparser.rst
index 7b0ce03..c114bf8 100644
--- a/Doc/library/htmlparser.rst
+++ b/Doc/library/htmlparser.rst
@@ -158,7 +158,7 @@
Method called when an unrecognized SGML declaration is read by the parser.
The *data* parameter will be the entire contents of the declaration inside
- the ``<!...>`` markup. It is sometimes useful to be be overridden by a
+ the ``<!...>`` markup. It is sometimes useful to be overridden by a
derived class; the base class implementation throws an :exc:`HTMLParseError`.