: One to many relationship and ObjectStateManager error

Understand basic navigation with Entity Framework Code First (4.3) with 1 to many relationship

http://patrickdesjardins.com/blog/understand-basic-navigation-with-entity-framework-code-first-4-3-with-1-to-many-relationship

Entity Framework 4.3: An object with the same key already exists in the ObjectStateManager

http://patrickdesjardins.com/blog/entity-framework-4-3-an-object-with-the-same-key-already-exists-in-the-objectstatemanager