I got copies of cards I owned but have disenchanted, like Worgen Greaser, before getting cards I have never owned. Is this intended behavior with the duplicate protection? If it is I guess I'm just crafting the cards I want instead of bothering with packs.
Yes and no. Duplicate protection only knows about cards you disenchanted since duplicate protection was added in 2020. If you disenchanted it before 2020, there's no record that you ever had it, so you can get it again.