I have had this exact dream scenario too - "you signed up for x course and today is the final worth 60% and you forgot you were signed up". Only twice since I

I have had this exact dream scenario too - "you signed up for x course and today is the final worth 60% and you forgot you were signed up". Only twice since I graduated many years ago. I think was latent exam related stress working it's way through my brain. I always hated the stress of 50% or higher exams in engineering courses and they were common. I never stressed while taking the exam, just the lead up to it. I don't think it's the mandella effect just your subconscious mind coming up with a worst case scenario of exam stress.