===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/mandoc/mandoc.1,v
retrieving revision 1.124
retrieving revision 1.125
diff -u -r1.124 -r1.125
--- src/usr.bin/mandoc/mandoc.1	2017/06/17 22:40:27	1.124
+++ src/usr.bin/mandoc/mandoc.1	2017/06/17 23:06:43	1.125
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: mandoc.1,v 1.124 2017/06/17 22:40:27 schwarze Exp $
+.\"	$OpenBSD: mandoc.1,v 1.125 2017/06/17 23:06:43 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -799,6 +799,11 @@
 or
 .Ic NetBSD
 keyword substitution as conventionally used in these operating systems.
+.It Sy "duplicate RCS id"
+A single manual page contains two copies of the RCS identifier for
+the same operating system.
+Consider deleting the later instance and moving the first one up
+to the top of the page.
 .It Sy "useless macro"
 .Pq mdoc
 A