I am 99% sure that the only reason MIT allows double majors is because high school seniors think they want it and won’t apply otherwise. For a very long time, you couldn’t do this at all - the closest was a double degree, which took I think 90 more units and you got two actual diplomas instead of one. Once the students get to the Institute they quickly discover that it’susually better to take classes of interest rather than chasing the credential.
The OP, however, seems to be rather credential-focused. That’s not a good match with MIT. Should he manage to transfer there - which is unlikely for reasons pointed out by many posters in this thread - I think it’s highly likely he will discover its not for him either.
Princeton requires Junior Paper and more substantial Senior Thesis as pre-requisites for graduation for all undergrads. Because of such rigorous requirements, a “double major” is not a possibility at Princeton. It’s for this reason why they call it “concentration” what other colleges and universities call “major.”
Princeton does, however, offer various and flexible “certificate programs” akin to what others call a “minor.” Some of the pertinent certificate programs that OP can consider to go with ECE concentration are, for example: Certificate in Financing; Entrepreneurship; Engineering Biology, etc. Students are not limited to one certificate; one can do more than one.
There is a wealth of academic and pre-career resources on campus, beginning with the faculty advisors at the residential college assigned. My suggestion for the OP is to explore these as opposed to placing much effort at a highly unlikely chance of a successful transfer.
As many have said here, I want to re-stress that the credential matters very little or not at all. My son (who is now at P) tells me that the courses you take, the degree you get, and the job you get afterwards, are pretty much independent of each other within reason. An example he gave me a week ago was a friend of his who is a Chemistry major from P doing a TCS PhD at Cornell.