Your question is not clear. But if you meant you first wrote 01 as your code and that is correct but you later changed it, your qualification code doesn't affect your merit in the NEET counselling. So it is acceptable. But if your question is different from what we guessed it to be, please help us understand the question in the comments section and we shall help you. You may even ask in your local language  and we shall try replying you with correct information.