The Plot thickens - or not?
My F3P has the two shown contacts that correspond to the contacts of the special back used for F3P + motordrive MD-4 and which indeed makes the red LED(s) light up. That is, if I remember correctly, one LED lights up for each exposure, another lights up and stays put while the film is rewound.
Thus it seems these two are related to the motordrive and not to any databack.