I originally intended to use IRF640 as an example, as for HexFET it is painfully obvious that there are separate parallel connected transistors. For typical BJ

I originally intended to use IRF640 as an example, as for HexFET it is painfully obvious that there are separate parallel connected transistors. For typical BJTs it depends on how you define "separate transistor". The structure in typical BJT has one contiguos junction, but its geometry is non-trivial enough that you can well think of it as multiple paralleled transistors.