Is it better to have models that have double faces or is it better to have a two-sided material instead? - Pipeline & Plugins - Epic Developer Community Forums
How to add Blender 2 sided material to one mesh - cgian.com
Normals — Blender Manual
Blender 2.93 | how to make Double Sided material - tutorial - YouTube
Beginning Blender User - Modeling Tips for Double Sided Polygons - YouTube