--- loncom/homework/essayresponse.pm	2002/07/25 20:51:39	1.11
+++ loncom/homework/essayresponse.pm	2002/07/26 20:27:33	1.12
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # essay (ungraded) style responses
 #
-# $Id: essayresponse.pm,v 1.11 2002/07/25 20:51:39 ng Exp $
+# $Id: essayresponse.pm,v 1.12 2002/07/26 20:27:33 ng Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -62,7 +62,10 @@ sub end_essayresponse {
     my $id  = &Apache::response::start_response($parstack,$safeeval);
     my $collaborators = $ENV{'form.HWCOL'.$id};	
     if ($collaborators =~ /[^\s]/) {
-	$Apache::lonhomework::results{"resource.$part.$id.collaborators"}=$collaborators;
+	my $previous_list= &HTML::Entities::encode($Apache::lonhomework::history{"resource.$part.$id.collaborators"});
+
+	$Apache::lonhomework::results{"resource.$part.$id.collaborators"}=$collaborators
+	    if ($collaborators ne $previous_list);
     }
     if ( $target eq 'grade' ) {
 	if ( defined $ENV{'form.submitted'}) {