Unsubscribe, the Double Furnace mod has been updated and the fix is no longer needed. (Quick change on the 0.17 version of raid's Double Furnace mod so the double smelting tech doesn't cost purple science anymore.)
The original DoubleFurnace has since been updated for newer Factorio versions. I would recommend the removal of this mod.
Thx, good to hear! It's already on deprecated state I don't think I can remove altogether.