Coal armor goes for a lot. Back when it was made tho I don't believe you got double exe tags for crafting it, but I could be wrong about that. I'm pretty sure crafted coal just has the [exceptional] tags, if any. You might want to check their color against shadow armor, if they aren't darker but are a different shade of color then it might be from someone smelting the old
NPC colored armors then crafting new armor with the ingots.