ErrorPage behaviour using JSP Template

Hello All,

I'm working on a JSP app. for a given API. I am using a template which
includes the others (Header.jsp,Left.jsp...) with the <jsp:include> into a
table.
In some cases of exceptions the errorPage comes properly, but sometimes
parts of the template appear twice just like if I use the  <jsp:forward>...
I've read the specs, but I seem to missed sg.
Should I use the <%@  include> and sendRedirect("...") in the template
instead?...Or save all exceptions?...
What is the common solution for the ErrorPage using Template for layout?
pls. help

Best Regards
Gabor