Hii,i am here to help you according to your query.I guess it depends on the college and Im not sure how this works. What I know is, the final year of BTech and 1st year of MTech are same so I guess you could skip you exams if allowed to and get your Btech degree only. However, there might be the case of paying full fees for the dual degree course. It just depends on your university or college.You have a great opportunity to do mtech, so don't loose that, leads higher salaries and easy promotions for life time. futher you need to persue mba immediately or after getting 2-3yrs. experience.

Hope,this information helpful for you.Goodluck.