mesh - Is this is double-sided plane? - Blender Stack Exchange
Double-Sided Material w/Solidify and Subdivision? - Materials and Textures - Blender Artists Community
normals - Disable double sided faces in Blender 3D View - Blender Stack Exchange
how to create double sided materials in blender - YouTube
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