I double majored in two unrelated fields. I don't think it was brought up once during interviews. It did make my life in college a bit easier since I could split my academic terms with half science/half nonscience for the other major. No cons, I really enjoyed the subject matter in both.

You're going to get a lot of neuroscience and molecular/cell biology in medical school with opportunities to do research there in both fields as well.

The one thing that will help you the most is being successful in your classes. Can you maintain a high GPA in two gruelling science majors?

The second thing that's going to help you not just get into med school, but help you match is published research. Will you have time with a double major to work on research?

Lastly, are you going to have time to do the other extracurriculars required for med school?

If yes, then it's worth considering. If not, then it might be time to choose which one you like more.