Well, this isn't a Perl question. What you are trying to do doesn't work because that's not how HTML works. It wouldn't work with a CGI program written in Cobol or APL either.

Of course, there's nothing preventing you from putting a fork as one of the first statements of your program, and do one "script" in the parent, and the other in the child.

But that wouldn't show up as two hits in your servers log files.

Abigail