First add the truncator (if there is none in the text itself), then closing tags

boards/templatetags/board.py

@@ -106,9 +106,10 b' def truncatenewlines_html(value, arg):'
 
                 current_pos = tag.end()
 
+        if not text.endswith(TRUNCATOR):
+            text += TRUNCATOR
         for tag in open_tags:
             text += '</%s>'.format(tag)
-        text += TRUNCATOR
     else:
         text = value