Hey Harshit,

Under obc category of du one requires a Non creamy layer obc certificate which is signed by the central government. It is issued to the people who are under central obc list and whose income is under 6 lakhs p.a. 

Du is very specific regarding quotas and hence any duplication or mistake may lead to cancellation of admission at the time of admissions. You need to get it authorised and signed by central govt. While admissions it might create problem for you as they don't entertain any excuses so better get it sooner. Also some colleges ask the income certificate in admissions for verification, so it would be advisable to carry the income certificate with you.

Good luck!