When importing gltf files into Godot I had some unexpected behavior. I'd made a model, exported it, the changed some colours and exported it again under a different name (several times). When importing into Godot, all models had the same colours as the material names were identical. I appreciate that you'd generally want all your models to share a common material set so this might be an edge case that's not worth addressing - but potentially either a checkbox to rename materials uniquely at export time, or a warning box when saving (/exporting) under a different filename might be handy?