Oh, thats interesting. I think it's confusion with nomenclature than training. If you dont have a doctorate, its hard to compare especially without knowing the training involved. From your description, it sounds like an MD-PhD, which takes 7 years, before residency for those who want to be physician-scientists (research and clinical work)...but reversed?? Or maybe a clinical fellowship for increased specialization and training??

Bachelors (4 yrs)-->medical school (earn MD, 4 yrs, or MD-PhD, 7 yrs)-->residency (4-7 years clinical medicine)-->optional clinical fellowship (1-3 yrs, and as many as you heart desires lol).

The PhDs in the US refer to strictly research and can be obtained right after Bachelors but I think most apply after masters depending on program entry criteria.