I'm putting in a couple of new electrical circuits in a new room. What
is the accepted practice when you are running two cables in the same
direction? I have drilled a hole in the studs to run one cable, but
with a 3/4 inch hole, I can fit two cables in the same hole. Is this
the right way to go, or is the norm to drill another hole a few inches
up and run the second cable separately?

Same question with respect to stapling cables coming in and out of the
boxes. Is it the norm to staple each cable separately to the stud, or
to secure wires running in the same direction from the box with a
single staple?