Discussion continued back at ... http://www.ifinity.com.au/Products/Support_Forums/forumid/8/postid/392/scope/posts/ ... apparently if EnforceSSL is true, and Page.Secure is false, it does a javascript reload via window.location.replace - which is not a redirect at all, it is just more duplicate content, the code is :
Response.Clear()
' add a refresh header to the response
Response.AddHeader("Refresh", "0;URL=" & strURL)
' add the clientside javascript redirection script
Response.Write("[html][head][title][/title]")
Response.Write("[!-- [script language=""javascript"">window.location.replace(""" & strURL & """)[/script> --]")
Response.Write("[/head][body][/body][/html]")
' send the response
Response.End()