Security Assist creates errors on previously working pages

I have tried this several times now, and each time I have, Security Assist destroys the code of all pages that were previously working. All I am doing is opening the Access Rules Manager and applying an existing rule to a new page that I have just created. When I click OK, the wizard takes over and opens and makes changes to ALL existing pages and consequently delivers bad code leaving me with this error:

Fatal error: Cannot redeclare WA_AuthenticateUser() (previously declared in /Users/username/Sites/website/webassist/security_assist/helper_php.php:28) in /Users/username/Sites/website/WA_SecurityAssist/Helper_PHP.php on line 46

This is from a page that was working prior to running the SA wizard.

Why does it insist on running changes on all pages when I have only amended one? The pages that were working are from PowerCMS and have the security rules from that wizard applied to them, the new pages I have created are from Design Extender.

As in my post from yesterday, I have tried copying and pasting the original SA code, but this gives me a too many redirects error and stops the page from working entirely! No spaces or blank lines this time though ;)

What's going on here? Every new page that I create can't have a detrimental effect on pages that existed prior to the single install extensions otherwise I will be having errors on dozens of sites should I have to add new pages to them!

Luckily again, I have duplicated my entire site folder, so I can just delete the now broken pages and go back to the before SA state, but I need to get a solution for this.

Thanks.