Index: wp-includes/taxonomy.php
===================================================================
--- wp-includes/taxonomy.php	(revision 17230)
+++ wp-includes/taxonomy.php	(working copy)
@@ -2270,6 +2270,14 @@
 		else
 			return new WP_Error('duplicate_term_slug', sprintf(__('The slug “%s” is already in use by another term'), $slug));
 	}
+	
+	if( $wpdb->get_var( $wpdb->prepare( "SELECT term_id FROM $wpdb->term_taxonomy WHERE term_id = %d AND taxonomy != %s", $id, $taxonomy ) ) ) {
+		$slug = wp_unique_term_slug( $slug, (object)$args ); 	
+		$wpdb->insert( $wpdb->terms, compact( 'name', 'slug', 'term_group' ) );
+		$term_id = ( int ) $wpdb->insert_id;
+		$wpdb->update( $wpdb->term_taxonomy, compact( 'term_id' ), array( 'term_id' => $id, 'taxonomy' => $taxonomy ) );		
+	}
+	
 	do_action( 'edit_terms', $term_id );
 	$wpdb->update($wpdb->terms, compact( 'name', 'slug', 'term_group' ), compact( 'term_id' ) );
 	if ( empty($slug) ) {