--- nntp.el~	2007-07-18 12:07:39 +0000
+++ nntp.el	2007-08-08 10:12:33 +0000
@@ -203,6 +203,14 @@
 server there that you can connect to.  See also
 `nntp-open-connection-function'")
 
+(defvoo nntp-xref-number-is-evil nil
+  "*If non-nil, Gnus never trusts article numbers in the Xref header.
+Some news servers, e.g., ones running Diablo, run multiple engines
+having the same articles but article numbers are not kept synchronized
+between them.  If you connect to such a server, set this to t, and Gnus
+never uses article numbers (that appear in the Xref header and vary by
+which engine is chosen) in order to refer to articles.")
+
 (defvoo nntp-coding-system-for-read 'binary
   "*Coding system to read from NNTP.")
 
@@ -1702,7 +1710,8 @@
 		    (match-string 1 xref))
 		   (t "")))
 	  (cond
-	   ((and (setq xref (mail-fetch-field "xref"))
+	   ((and (not nntp-xref-number-is-evil)
+		 (setq xref (mail-fetch-field "xref"))
 		 (string-match
 		  (if group
 		      (concat "\\(" (regexp-quote group) "\\):\\([0-9]+\\)")