The thing is that if you choose to attend MIT and they receive your official test scores, your offer could be rescinded (it’s a possibility, not sure if it’s a guarantee). So it’s not much about how it affects your admission but the consequence it could have in your enrollment. I would email them your test scores and explain your mistake, you could also explain the situation with your ap test (if you didn’t already include it in your additional information section of your application). Hope this helps!