I agree with Jota_jota. Personally, I didn't even know you can get an MPH from online. Ultimately, the best is to look at it from an adcom's perspective. These people got their MDs, MPHs, PhDs, and MD/PhDs through traditional methods. At best they would just not think any less or any better of the degree, at worse they could think of it as inferior to what they did (or what their colleagues did). Thus they may focus on your more traditional work, such as undergrad, and if that is not competative either, then that certainly does not look good.