Remove duplication.
diff --git a/Doc/library/http.client.rst b/Doc/library/http.client.rst
index 9b1ab0f..c1ce15b 100644
--- a/Doc/library/http.client.rst
+++ b/Doc/library/http.client.rst
@@ -435,7 +435,7 @@
Set the host and the port for HTTP Connect Tunnelling. Normally used when it
is required to a HTTPS Connection through a proxy server.
- The headers argument should be a mapping of extra HTTP headers to to sent
+ The headers argument should be a mapping of extra HTTP headers to sent
with the CONNECT request.
.. versionadded:: 3.2