To verify that the Add Button, when clicked, navigates to the correct page/form, you would need to check both the locations of the button.
Although, the buttons would have the same label and design, they are 2 separate web elements located in 2 different pages.
Unless the buttons are created dynamically using the same function/method (piece of code) in the back-end, chances are one or both of them may have incorrect/different link.
Considering this, it would be nice to check the buttons works the same in both locations.
- you can run the checks for both locations in a single test case, first by navigating to the button via the Dashboard, then in the same case navigate to the View User Module to check the button.
- You can also write 2 separate test cases to verify the buttons functions right in the both locations.
Personally, I would go with the first option.