What should I choose: IIT Roorkee metallurgy or IIT BHU materials dual degree?

You can go with IIT Roorkee Metallurgy rather than IIT BHU. The four-year course is good, and you can further pursue a master’s if you are interested in this field. Both institutes are good at providing effective study materials, but there are other benefits available if you choose IIT Roorkee. They are:

• The Metallurgy department at IITR is the top in packing material research in India
• They are best for coding culture, machine learning, software, and so on
•  You will have a culture of interdisciplinary study, and with the presence of the Center of Excellence - Nanotechnology, which is led by a Professor of Metallurgical and Materials Engineering, you will have the added advantage of working in the best labs.

So, IIT Roorkee is much better than IIT BHU.