Yes, there is a bias against DOs in academic programs in general.
I was a fellow at an academic program and did some resident interviewing so had a superficial overview of the process
The program gave a few courtesy interviews to DOs who did away rotations at one of the affiliated hospitals but I heard the assistant PD tell me point blank they were not going to match with them.
All things being equal, for a lot of these academic programs, MD > DO. Hell, even if the MD is weaker they will still lean towards them.
Not much you can do about it at this point. It will slowly change but that will require DOs to get involved in academia to a certain degree.