Sarvesh ;

I understand your concern ; but don't worry. The NEET 2020 organizing body is going to check every application after the date for applying ends. If they find any irregularities in your application such as your passport photo and postcard photo, they'll inform you via a message to your registered phone number and email address.

It's most likely that they'll find your mistake and ask you to rectify it during the correction window. It is to begin from 15th Jan and continue up until 31st of January. During that period you can upload the postcard size photo in it's place.

But by some chance they don't see through it and don't ask (or) send you any message; than you're good to go and there's no need to change anything.

Hope this helps!