Should we have both for better SEO? Does having og description, override meta name description?
Meta Description = Search Engines, OG Descriptions = Social Platforms
Meta Description is used by Search Engines Bots, while the OG (The Open Graph protocol) is used by Social Media Bots, therefore if you want 'extra' information on Social Media sites then you should opt to use both the META and OG tags. You can find a list of whom uses OG below.
The Open Graph protocol is supported by a wide range of social platforms which includes: