Wow, that's interesting.
Looking at her CV and biography, the dates of her undergraduate years and post-graduate experience are too consistent for this to simply be a typo.
If we assume that Penn didn't allow any sort of shortening of the MD, then it implies that she did medical coursework and PhD research at the same time.
Observations:
-she didn't do a residency. if she wasnt interested in one in advance, its possible she prioritized her md grades less than her peers.
-by the time she submitted her dissertation, she had 2 first-author journal publications( langmuir, biotechnology progress), and several conference publications.
-she did combined experimental and computational work. She has a journal paper with her as first-author and her advisor as the only other author, which (probably) means that she was indeed actually running experiments, not just doing computational work with other people data.
From looking at the methods that her dissertation abstract mentions, and publications that her advisor had prior to 1993 (it looks like he did adhesion studies under similar conditions with different ligand-receptor pairs), it might be that the experimental methods she was using during her dissertation were already pretty robust.
Pretty insane though... probably a combination of an exceptional person and exceptional circumstances.