Dependency injection in AngularJS is done by providing the names of the desired dependencies. Providing the same name multiple times is redundant since the AngularJS injector uses a cache for instantiated dependencies.

Only include the name of each dependency once.

The following example shows an AngularJS controller with $cookies as a duplicate dependency.

This is problematic, since the programmer could be led to believe that the two parameters $cookies1 and $cookies2 are different instances, which they are not.

Instead, the dependency should only be listed once:

AngularJS Developer Guide: Dependency Injection.