My DD has two also. I figured one of two things: administrative error or the MOC has two NOMs to give this year (authorized 5, so every 4th year MOC has two on the average). 2 cents
More than likely, the MOC has two vacancies. Check the portal, it should something like AA121 and AA122. First two letters should be your state, first two numbers should be the congressional district, and last number should be the corresponding vacancy..