I'm not sure what you mean by "practicing osteopathy." DOs and MDs at work look the same with the exception of the OMM specialists or the very few FM/peds docs that do some OMM in their practices.
In shadowing, schools hope that you get some kind of view of what it is like to practice medicine today. In shadowing DOs, they hope that the DO will have some sort of discussion with you about the DO philosophy, which, quite honestly, is no different than how the vast majority of MDs practice as well.