The quick answer is that NO, your candidature will not be affected because of a typographical error in your marksheet. You just have to get an affidavit made and you'll need to xerox that affidavit and have to produce it at the time of counselling for scrutiny. Just do this and then relax, as your work is over now.

So, don't worry and focus on your examinations. Hope I have answered your question. All the best!