Having problem with 2D Roguelike tutorial Error: " error CS0101: The namespace `Completed' already contains a definition for `BoardManager'"

I am having problems with 2D Roguelike and I get an error code; error CS0101: The namespace `Completed' already contains a definition for 'BoardManager'` Anytime if "namespace Completed" is removed i get error CS8025: `Parsing error`. Can someone help me and explain the problem because I do not these errors