Dual Degree means that you will be awarded two degrees at a time. The dual degree is essentially equally to Integrated MTech degree course. This means that over a 5 years of time you will be awarded the BTech and MTech degree simultaneously. So this course isn't awarded in every college so if you get a chance you can do it as in this course you will save 1 year of time because if you wish to do BTech and MTech separately then BTech is 4 years and MTech is 2 years i.e., 6 years. So if you have dual degree course then you will essentially save 1 years.

For Top dual degree engineering college you may visit the link below:

https://engineering.careers360.com/colleges/list-of-dual-degree-engineering-colleges-in-india

I hope this answer helps. All the very best for your future endeavors!