I saw a similar thing to this in a 3D printing forum but as the designer did not answer any requests to share the STL file, I thought that I would have a go myself.

This is a replica of a Victorian goblet with an external profile which resembles that of a face - and as it is symmetrical, it is the same face on each side! My limited research suggests that similar goblets were made like this with the profile of Queen Victoria's face on one side and Prince Albert's on the other - my design skills are not good enough for that sort of detail!