Do not add a second major purely as a consulting signal. Firms are much more interested in strong overall academic performance and what you accomplished outside the classroom.

If the second major is genuinely valuable to you and you can handle it without sacrificing the rest of your profile, it can be worthwhile.

But choosing academic complexity for appearance alone is rarely a good trade if it meaningfully damages grades, internships, or leadership involvement.

I would pick strong GPA + one major every time for recruiting.

Do the second major because you want it, not because MBB will count majors.