Not sure or why it matters, but I think the guidelines are if you have been deemed sufficient to continue from the pre candidate questionnaire and have completed 50% of your candidate application the DoDMERB event is triggered and the candidate is authorized to complete the DoDMERB paper and schedule the examinations - physical, hearing, and vision.
All SAs and I believe ROTC have the same physical and DoDMERB sends the results to each department/SA/ROTC that requests it
So whichever agency you met the 50% threshold first probably initiated the DoDMERB request