minor: typo fix

Author: Sam Kleinman

source/administration/backups.txt

@@ -423,7 +423,7 @@ server/database/collection (or part of a collection using of query,)
 even when the database is running and active. If you run
 :program:`mongodump` without any arguments the command will connect to
 the local database instance (e.g. ``127.0.0.1`` or ``localhost``) and
-create a database backup in a in the current directory named
+create a database backup in in the current directory named
 ``dump/``.
 
 .. include:: /includes/note-mongodump-compatibility-2.2.rst