When applying to BS/MD programs you typically have to apply to the undergraduate college first and then, if accepted, the medical school will look at your application. One of the questions that several of my students have asked is does the medical school see what has been submitted to the undergraduate college. The answer is ….
Most medical schools will have access to the undergraduate application, and essays, if they want to review them. This is particularly true when the college and medical school are part of the same university. But even if they are separate institutions, medical school admissions people may have access to the college application essays.
This does not necessarily mean that they will view them but you should start with the assumption that all of your application information is available to everybody from the college and medical school.
That is part of the reason why you don’t want your common app personal statement to be about why you want to be a doctor when you will be writing the same essay for the medical school. The other reason is that the essays are your chance to communicate how well you write and also showcase what an interesting person you are. By writing similar essays, you are wasting this opportunity.