As Designed Stellaris - Habitats: Industrial districts on world without mineral/energy/science provides artisans x2, rather than artisans/metallurgists x1 each

[Gold Digger]

Hello!
Yes, this is intentional. The way that the planet/habitat designation works is that if you set your habitat to be a Factory Station it shifts one Metallurgist job to an Artisan job for each Industrial district, giving you two artisans.