The provisions of this Act with regard to certificates of the validity of a patent, and to the remedy in case of groundless threats of legal proceedings by a patentee, shall apply in the case of registered designs in like manner as they apply in the case of patents, with the substitution of references to the copyright in a design for references to a patent, and of references to the proprietor of a design for references to the patentee, and of references to the design for references to the invention.