Are this holes normal? They are not slotted.
This hub is obviously used. The dents at the edge of every second hole are wear caused by spokes that were mounted in a way they leave the hub at the outside. The spoke hole inbetween that are less dented had the spoke leave the hub on the back side, and the the less sharp heads of the spoke don't cause this much wear.
If you want to build a new wheel with that hub, I recommend you to either use exactly the same spoke scheme as in the wheel the hub came from (so the new spokes perfectly align with the wear marks) or mounting the outside spokes in holes that previously were used for the inside spokes and the other way around, the the weak marks don't affect the new spokes.