Yes, it's a possibility that your script is executing twice. You said in the OP "the exit is getting ignored" - that is such an unlikely bug that it's practically impossible. So you need to keep track of the state to detect and prevent multiple executions of the script.

Perhaps it's time to develop a test case that reproduces the problem, like a few really short CGI scripts that redirect to each other, similar to what your code is doing now. Post it here so we can help you debug, otherwise we're left guessing and all the debugging is up to you.