The second click could be calling the CGI script again within the limits of the gettimeofday() function. While you could improve this by increasing the granularity of the function, this would remain unscalable, you should add a random element to $v which would allow the session token to be unique, and also from a security perspective to make the session token less predictable.

CGI::Session may offer what you require, or Apache::Session::Generate::ModUniqueId

Update:Good observation by ww. In my haste I missed the presence of Time::HiRes.

Could you retry with verbose logging of the uniquid() and check_reload() functions? (This may of course prevent a race condition from occuring, or it may demonstrate the issue,)

The fact that you've tried adding a random element to $v without resolution troubles my understanding :(

In reply to Re: (CGI) Prevent a reload from resubmitting a form by Utilitarian
in thread (CGI) Prevent a reload from resubmitting a form by fmk

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