If one builds more than one stone furnace and then interacts with other than the oldest one currently build the tasks do not progress. But one should ideally be able to continue in the tutorial with any of their furnaces, not just the oldest build one.
Building furnace F1 and then furnace F2 gets you to situations like:
- opening F2 does not finish "open furnace", only opening F1 does
- then putting iron into F2 does not finish "put iron into furnace", you need have it in F1
- then putting fuel into F2 does not finish "put fuel into furnace", you need to have it in F1 together with some iron
- taking 5 iron plates from F2 does not finish "take plates from furnace", you need to take at least 1 from F1