If you have passed 12th from state board in 2019,and wish to appear in NEET 2020, so you can fill the Code 02 in the application form. The qualifying examination code for NEET 2020 for droppers will also be Code 02.  Beacause you have completed a period of 12 years under Higher/Secondary examination , which is equivalent to Class 10+2 , so you can opt code 2.

If you have already applied for an update, you can give the UID number. Also make sure that took a hardcopy of new Aadhar card before the exam. It will be verify at the centre