Unused slots in the stepper Motor
There are many motors that have six wires and can be either used as a bipolar motor or a unipolar motor, your motor is probably one of them.



There is a chance that these two points are actually dummy ones and not connected but you can easily check with an Ohm meter, if each one has a low resistance with eather of the two sides of the coil (the resistance will also be half of the total) then you can use it as a unipolar too.

Refer to this How to figure out the internal wiring of a stepper motor using a meter and a battery



The motor specs seems to be located here

Your motor code leads to this datasheet that has a six wire pinout

There is also this  datasheet in the same link, in page 6 there is a guide about the model number interpretation