diff --git a/C4/AuthoritiesMarc.pm b/C4/AuthoritiesMarc.pm
index 00d57b0142..cd68b4afbd 100644
--- a/C4/AuthoritiesMarc.pm
+++ b/C4/AuthoritiesMarc.pm
@@ -51,6 +51,7 @@ $VERSION = 0.01;
 	&AUTHaddword
 	&MARCaddword &MARCdelword
 	&char_decode
+	&FindDuplicate
  );
 
 sub authoritysearch {
@@ -844,6 +845,46 @@ sub nsb_clean {
 	return($string) ;
 }
 
+sub FindDuplicate {
+	my ($record,$authtypecode)=@_;
+	my $dbh = C4::Context->dbh;
+	
+	warn "".$record->as_formatted;
+	# search duplicate on ISBN, easy and fast...
+	my $sth = $dbh->prepare("select auth_tag_to_report from auth_types where authtypecode=?");
+	$sth->execute($authtypecode);
+	my ($auth_tag_to_report) = $sth->fetchrow;
+	$sth->finish;
+	# a more complex search : build a request for authoritysearch
+	my (@tags, @and_or, @excluding, @operator, @value, $offset, $length);
+	# search on biblio.title
+	warn " tag a reporter : $auth_tag_to_report";
+	if ($record->fields($auth_tag_to_report)) {
+		my $sth = $dbh->prepare("select tagfield,tagsubfield from auth_subfield_structure where tagfield=? and authtypecode=? and tab >= 0");
+		$sth->execute($auth_tag_to_report,$authtypecode);
+		warn " Champ $auth_tag_to_report present";
+		while (my ($tag,$subfield) = $sth->fetchrow){
+			if ($record->field($tag)->subfields($subfield)) {
+				warn "tag :".$tag." subfield: $subfield value : $record->field($tag)->subfield($subfield)->as_formatted";
+				push @tags, "'".$tag.$subfield."'";
+				push @and_or, "and";
+				push @excluding, "";
+				push @operator, "contains";
+				push @value, $record->field($tag)->subfield($subfield);
+			}
+		}
+	}
+ 
+	my ($finalresult,$nbresult) = authoritysearch($dbh,\@tags,\@and_or,\@excluding,\@operator,\@value,0,10,$authtypecode);
+	# there is at least 1 result => return the 1st one
+	if ($nbresult) {
+		warn "$nbresult => ".@$finalresult[0]->{authid},@$finalresult[0]->{summary};
+		return @$finalresult[0]->{authid},@$finalresult[0]->{authid},@$finalresult[0]->{summary};
+	}
+	# no result, returns nothing
+	return;
+}
+
 END { }       # module clean-up code here (global destructor)
 
 =back
@@ -858,6 +899,9 @@ Paul POULAIN paul.poulain@free.fr
 
 # $Id$
 # $Log$
+# Revision 1.12  2005/04/05 09:58:48  hdl
+# Adding double authority search before creating a new authority
+#
 # Revision 1.11  2005/03/07 08:55:29  tipaul
 # synch'ing with 2.2
 #
diff --git a/authorities/authorities.pl b/authorities/authorities.pl
index 76e008e725..e7209395e0 100755
--- a/authorities/authorities.pl
+++ b/authorities/authorities.pl
@@ -334,12 +334,30 @@ if ($op eq "add") {
 	}
 	my $record = AUTHhtml2marc($dbh,\@tags,\@subfields,\@values,%indicators);
 # MARC::Record built => now, record in DB
-	if ($is_a_modif) {
-		 AUTHmodauthority($dbh,$authid,$record,$authtypecode);
+	# check for a duplicate
+	my ($duplicateauthnumber,$duplicateauthid,$duplicateauthvalue) = FindDuplicate($record,$authtypecode) if ($op eq "add") && (!$is_a_modif);
+	my $confirm_not_duplicate = $input->param('confirm_not_duplicate');
+	# it is not a duplicate (determined either by Koha itself or by user checking it's not a duplicate)
+	if (!$duplicateauthnumber or $confirm_not_duplicate) {
+		# MARC::Record built => now, record in DB
+		if ($is_a_modif) {
+			AUTHmodauthority($dbh,$authid,$record,$authtypecode);
+		} else {
+			($authid) = AUTHaddauthority($dbh,$record,$authid,$authtypecode);
+		}
+	# now, redirect to additem page
+		print $input->redirect("detail.pl?authid=$authid");
+		exit;
 	} else {
-		($authid) = AUTHaddauthority($dbh,$record,$authid,$authtypecode);
+	# it may be a duplicate, warn the user and do nothing
+#		build_tabs ($template, $record, $dbh,$encoding);
+#		build_hidden_data;
+		$template->param(
+ 			duplicateauthnumber		=> $duplicateauthnumber,
+ 			duplicateauthid				=> $duplicateauthid,
+ 			duplicateauthvalue				=> $duplicateauthvalue,
+			 );
 	}
-	print $input->redirect("detail.pl?authid=$authid");
 #------------------------------------------------------------------------------------------------------------------------------
 } elsif ($op eq "addfield") {
 #------------------------------------------------------------------------------------------------------------------------------
diff --git a/koha-tmpl/intranet-tmpl/default/en/authorities/authorities.tmpl b/koha-tmpl/intranet-tmpl/default/en/authorities/authorities.tmpl
index 4f142c3591..072b3849ee 100644
--- a/koha-tmpl/intranet-tmpl/default/en/authorities/authorities.tmpl
+++ b/koha-tmpl/intranet-tmpl/default/en/authorities/authorities.tmpl
@@ -19,6 +19,16 @@
 
 <br><br><br><br><br><br><br><br><br><br><br>
 
+<!-- TMPL_IF name="duplicatebiblionumber" -->
+	<div class="problem">
+		<p>Duplicate suspected with <a href='javascript:openWindow("detail.pl?authid=<!-- TMPL_VAR name="duplicateauthnumber" -->&popup=1", "Duplicate Authority")' class="button catalogue"><!-- TMPL_VAR name="duplicateauthvalue" --></a></p>
+		<p>You must either :</p>
+		<ul>
+			<p><input type="checkbox" value=1 name="confirm_not_duplicate">confirm it's not a duplicate (and click on Add Auth again)</p>
+			<p>Go to <a href="authorities.pl?authid=<!-- TMPL_VAR name="duplicateauthid" --> class="button catalogue">edit items</a> from this duplicate Authority</p>
+		</ul>
+	</div>
+<!-- /TMPL_IF -->
 <!-- TMPL_LOOP NAME="0XX" -->
 	<!-- TMPL_IF name="tag" -->
 		<p class="MARCtag">