Index: date.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/date/date.module,v
retrieving revision 1.32.2.43
diff -u -r1.32.2.43 date.module
--- date.module	3 Jul 2007 11:06:07 -0000	1.32.2.43
+++ date.module	28 Aug 2007 09:30:00 -0000
@@ -1064,6 +1064,10 @@
     return '<span class="date-display-single">'. $date1 .'</span>';
   }
   else {
+    // if difference is less than 1 day, display ony end-time
+    if($dates['value2']['object']->db->timestamp - $dates['value']['object']->db->timestamp < 24*60*60)
+      $date2 = date_show_date($dates['value2']['object'],'H:i','local');
+      
     return '<span class="date-display-start">'. $date1 .'</span><span class="date-display-separator"> - </span><span class="date-display-end">'. $date2 .'</span>';
   }
 }