Wouldn't matter in this case. helloWorld() has the exact same code on both definitions. I'd like the compiler to just pick one definition and throw the rest of them away. Another way would be to check the actual code of the definitions - if the code were equal, keep one of them; if one definition had different code, show an error or something.
In the first place, having such duplicate code probably means that you are not thinking right, or were careless. That the compiler tells you sooner about the potential problem instead of later is a Good Thing, in my opinion.

Consider the likelihood that two non-trivial functions would be identical. I think that it is not worth the trouble trying to do that kind of duplicate code elimination when most of the time that it happens, you have to resolve it manually anyway.