mesh - Is this is double-sided plane? - Blender Stack Exchange
Turn off double-sided faces for sculpting... - Modeling - Blender Artists Community
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
Turn off double-sided faces for sculpting... - Modeling - Blender Artists Community
UE4 – Creating two sided material effects using the TwoSidedSign node – Oded Maoz Erell's CG Log