Off the top of my head, so i will (as usual) apologize in advance for syntax or other errors, but i think this will give you the 2 values you are looking for.
//{Formula_D9450}
numbervar D9;
IF {Data.CPTCode}="D9450" then D9 := D9 + {Data.Allowed}
else D9 := D9;
D9
//{Formula_Not_D9450}
numbervar N9;
IF NOT({Data.CPTCode}="D9450") then N9 := N9 + {Data.Allowed}
else N9 := N9;
N9