Your BusinessFormValidation module is using the CGI::Application module - I think you should check the docs for it.

The CGI::Application instance is what is printing out the extra header, that's what it's supposed to do.

If you're only using CGI::Application::ValidateRM for data validation, I think you should be using Data::FormValidator instead.
If you do want to use CGI::Application, read the docs and let it do the bits it's supposed to, such as loading CGI and printing the header, etc...