Our EdTech platform is experiencing an issue where students are sometimes enrolled in courses twice due to duplicate form submissions. I need a developer to fix this backend PHP bug. We're observing duplicate entries for course enrollments from our main student registration form. I suspect a race condition or an issue with how our PHP backend handles rapid or repeated submissions. I need an experienced developer to pinpoint the exact cause and implement a robust solution to prevent any further duplicate enrollments. Our platform runs on a standard LAMP stack.