Is dual degree(btech + mtech) in iits cause any problem during campus placement? Is it right to take dual degree course which gives btech in electrical engineering and mtech in power electronics?what is its future

No dual degree does not cause any problem, infact it gives you the two degress. But there is not any significant difference in the salary offered compared to Btech. If you are getting this in older IITs then only prefer otherwise you may think of other option.