There's not much of a difference in terms of placements or campus. Go for your interest.
EE comprises power transfer and machines, whereas Mechanical deals with heavy tools and machinery work.
You should choose IIT Kharagpur Mechanical Engineering dual degree due to following reasons:-
Let me ask you genuinely, are you sure a high package is enough to satisfy you irrespective of the type of work you will be doing? If you go for Electrical Engineering at IIT Roorkee for lucrative placements and end up with average grades and a below-average package, you suffer. All the more even if you get placed with a good package but have no interest in the job, then after some time it will become a burden for you.
The first and foremost thing is to change your mindset and look at things from a bigger perspective. Your criteria for judging a certain should include much more than just placements. You can analyze some things like checking what intrigued you the most during your +2 levels.
If it is Mechanics, fluids, and Thermodynamics that excites you, then you should go for Mechanical Engineering.
If you are inclined towards Electric circuits, Electromagnetism, then your department is Electrical Engineering.
Basically, placements depend on your academics and grades. It’s likely that a top student from Mining ends up with a higher package than an average student of Electrical Engineering. Money and education combined should be the determining factors and not money alone. After all, your education must motivate you enough to secure the best package.