I am applying for Neuroscience for Georgia Tech, and considering adding Biomedical Engineering as “an additional major of interest” (as it asks for).
But apparently getting into engineering college is harder than science, so will my choice disadvantage me? Or should I just choose Biochemistry as he the second interest in order to get in?
Rather than fixating on slight discrepancies between each specific school (Georgia Tech as a whole is selective,) think about the story your application’s trying to tell: if someone was to look at your essays, extracurricular activities, letters etc. would they be certain of your interest in x or y major?
I did not apply here, but if it’s separated into schools, then Admissions Officers will likely consider you for admission into your first choice school (so science or wherever neuroscience is located) before considering your second choice school. I would recommend confirming with the admissions website or the admissions office to be sure: that’s why they’re there! 
Hope that helps!