It is advised that you immediately write to them stating the mistake that has occurred. Based upon their response, you canact further. However, as I see it, it should not cause you any problem as far as the conduction of exams and declaration of results are concerned. It might be a problem at the time of counselling. But if you inform them beforehand and have a copy of the email conversation, it can be fixed. Do not worry. 

To know more about the AIIMS Application Form keep reading Careers360 using the link given below: https://medicine.careers360.com/articles/aiims-mbbs-application-form

Thanks,