Hello Aspirant,

Sometimes when this sort of problem happens with anyone, he or she should Immediately contact and tell the invigilator. The invigilator may give you a new sheet for answering.

But, now, since it has happened with you, and you have bubbled the correct one, there should be no problem arising from it perhaps. You could have cut the wrongly bubbled number with a pencil and keep the way it was.

Now, the authorities would consider and verify  your original roll no. from their side on computer maybe and then verify what roll no. you have written or bubbled. Even if you have written your roll no. correctly and bubbled some incorrect no. then also authorities could consider it and it won't be rejected in anyway.

Hope that helps. Good luck