Math and Science Subject Test scores aren’t interchangeable, so a good science test score wouldn’t make the Math2 score redundant. When schools were recommending the tests, a math and a science were a common recommendation for many schools.
I’m pretty sure 780 will be average to above average anywhere that is still considering Subject Test scores. So yes, go ahead and submit it everywhere.
(Fwiw, Caltech’s 25-75% scores have been 800-800 since 2017. I think the last time MIT reported was 2017, when it was 760-800).