It's pretty common to have different diagnoses either over the years, or from different docs.
But does it really matter if they call it a or b? Should we just focus on living the life we want within our limitations, and not let it define us? They have to call it something but none of us fit into little boxes, I have BPII but also can have symptoms that fit into some of the other diagnoses, so instead of wondering and worrying, I just try to adapt and focus on symptom and life management.