Uhhh, wait a second....
Does that mean if you have a function for converting indexes, only the first function will fire, bugging out your JASS???
Ex.
udg_UnitArray[IndexFunction(u1)] == udg_UnitArray[IndexFunction(u2)]
Or maybe...
udg_UnitArray[IndexFunction(u1)] == udg_UnitArray[IndexFunction(u2)] and udg_UnitArray[IndexFunction(u3)] == udg_UnitArray[IndexFunction(u4)]