Duplicate (Click)
From Mario Fan Games Galaxy Wiki
Duplicate objects are nothing more than individual instances of an object. During edittime, they all share the same information; a change in one object affects all its duplicates. During runtime, however, they can take on their own settings and traits, but they still all share the same code.
Cloned objects, on the other hand, are entirely different objects and not actual instances; however, they inherit the settings of their "parent" object as their defaults, which may cause confusion.