[Erwin]

Actually, they are VERY interesting questions. In Autralia, common law and legislation automatically gives an author copyright over a work for life, and then 50 years after his or her death.

"Before an infringement suit may be filed in court, registration is necessary for works of U. S. origin."

I interpret that to mean that in order to sue another person for copying your work, you need to register your design as your own copyright (regardless of if the other person had registered his version of your work). So you get 2 copyright registrations for similar designs - then you fight it out in court, with one accusing the other of infringement. That's how I assume it would work.