--- /usr/local/lib/xemacs/gnus/lisp/gnus-sum.el-5.6.3	Fri Mar 27 21:14:05 1998
+++ /usr/local/lib/xemacs/gnus/lisp/gnus-sum.el	Fri Mar 27 21:44:35 1998
@@ -2960,7 +2960,8 @@
   (let ((headers gnus-newsgroup-headers)
 	(deps gnus-newsgroup-dependencies)
 	header references generation relations
-	cthread subject child end pthread relation new-child)
+	cthread subject child end pthread relation new-child
+	refs-uniq)
     ;; First we create an alist of generations/relations, where
     ;; generations is how much we trust the relation, and the relation
     ;; is parent/child.
@@ -2972,17 +2973,21 @@
 		   (not (string= references "")))
 	  (insert references)
 	  (setq child (mail-header-id header)
+		refs-uniq (list child)
 		subject (mail-header-subject header))
 	  (setq generation 0)
 	  (while (search-backward ">" nil t)
 	    (setq end (1+ (point)))
-	    (when (search-backward "<" nil t)
-	      (unless (string= (setq new-child (buffer-substring (point) end))
-			       child)
-		(push (list (incf generation)
-			    child (setq child new-child)
-			    subject)
-		      relations))))
+	    (when (and (search-backward "<" nil t)
+		       (not (member (setq new-child
+					  (buffer-substring (point) end))
+				    refs-uniq)))
+	      (push new-child refs-uniq)
+	      (push (list (incf generation)
+			  child (setq child new-child)
+			  subject)
+		    relations)))
 	  (push (list (1+ generation) child nil subject) relations)
 	  (erase-buffer)))
       (kill-buffer (current-buffer)))