Your DoDMERB exam is good for 2 years. Each commissioning source qualifies the candidate. So a qualified for ROTC does not automatically transfer. USMA will ask DoDMERB if you are qualified. If you meet USMA standard you will be qualified for USMA. There may be subtle differences between AROTC and USMA. They may be identical. It is highly likely that you will be qualified for USMA if you were qualified for AROTC.