Guide on adding a new model, animation, and creature to HoMMV

I'm just asking if there's a way to make it "double-sided" in these hero xdb materials. Because I'm not 100% sure, but it seems like there is.

Added 1 minute ago
By the way, I checked the model, and I collapsed the mesh into a single vertex for testing. After that, some of the polygons actually started disappearing when imported into the game.