Getting error when starting the game:

Failed to load mods: File not found:SteelDoubleFurnace/graphics/entity/steel-double-furnace/steel-double-furnace-base.png

This is very odd because I don't get this when I load it. Checking the mod I'm thinking I see where it comes from and if you use non-hr graphics then it makes sense because I didn't modify those correctly.
I think it should be fixed now, tell me if the mod loads correctly.

I was not using hr graphics, loaded just fine now. Thanks :)

Ok good.
I didn't change anything for non-hr graphics so you can't make the difference between normal and double steel furnaces ingame but hopefully it's still nice.

Found a new bug, mining double furnaces returns normal steel furnaces :P and the picture when placed is a bit to the right compared to the hitbox.