With the coils in parallel, you have 12 watts/4 Amps in each 3 Ohm coil at 6 Volts, yes, but to feed those 2 coils the provari would have to put out the 24 watts / 4 Amps. ( 2 x 12 watts)
Which it can't.
2 x 3 Ohm coils in parallel consume the same power as a 1,5 Ohm coil.