You will have to visit MDU Rohtak, to obtain a duplicate degree certificate. Carry your ID proof, marksheet, provisional certificate, and college ID along with you. Fill out the MDU Rohtak application form for duplicate degree certificate. The required details to fill out the application form are as follows - 

• Name of the certificate required
• Reasons for applying
• College name/ university
• Course
• Passing year
• Roll no (University)
• Marks 
• Address on which the certificate needs to be delivered

Submit the duly filled out application form at the result section. The university will take around 15-20 days to send the duplicate degree certificate. 

Collect all of your credentials and documents including ID proof, Mark sheets (if possible), College ID a minimum of 5 copies of each of them. The procedure is as follows:

• Get a form for a duplicate degree from the "Information Center" which is 100 meters from the University's Main Gate No 1.
• Fill out the form and take it to the Results Branch, which is located across the street from the DDE (Department of Distance Education) building.
• In the Results Branch, look for your Department. It is R3 for B.Tech.
• Submit the form there, and a duplicate degree certificate will be sent to you within 15–20 days.

Most probably, you will receive a phone call through which you will be informed whether your duplicate documents are ready or not. 

Alternatively, you can visit the campus of MDU Rohtak, and the staff members there would guide you through the entire process in case there have been some changes in the procedure.