No. To ensure consistency, a constant should be defined only once, in one interface.
However, it is OK if two interfaces include the same method header. A class that implements both interfaces only needs to provide one complete method definition to satisfy both interfaces.
An interface can be made public.
This is usually what is done.
When a class or interface is public it must be the only public
class or interface in the file that contains it.
Can an interface extend another interface?