Since these are direct copies the general approach is to use flood lights positioned at 45 degrees to the subject. I'm assuming you have disabled your camera's built-in flash. If you're working in a room with light walls, you might consider covering the wall directly reflecting back to the subject with black seamless background paper. You might even have to cover the camera/tripod and yourself with black cloth as you shoot. I'm surprised your polarizing filter is not helping. The items in shadow boxes will undoubtedly require fiddling with the lights to get even illumination. Feathering the lights--catching the edges of the light beam--sometimes works.
This all harkens back to my studio days back in the mid-sixties when we had to photograph highly polished stainless cook ware for a catalogue. That was nightmare stuff.