I recently applied at the American Embassy, New Delhi, for a new F1 visa for my PhD program. After the interview, my passport was collected by the embassy and my case was put under Administrative Processing - 221(g).
Now I don't know if I will get my visa in time for my classes. However, I still have an F1 visa valid until 2018 from my previous program (different university, same SEVIS), so I was wondering if I could just withdraw my application, get my passport back and fly on that visa. Would this create any problems for me in the future? Or maybe has the embassy canceled my old visa when I submitted it?