Someone ripped dimensional lumber with a 45 degree cut on top, a perfect baseboard for what we wanted. Unfortunately there are saw marks that I was hoping would disappear with sanding and painting. No luck.

How do I conceal these saw marks? Fill them with wood filler and sand? They aren't deep but if I sand too much it's going to mess up dimensions and hence how they meet up. There's a coat of primer and 2 coats of paint so far on them.