Both tautologies – known in the puffed-up jargon of linguistics as "contrastive focus reduplications" – have a precise meaning.
Energy has a precise meaning in physics that does not always correspond to everyday language, and yet a precise definition is somewhat elusive.
As you realize to your dismay, in this context "single" is a technical term with a precise meaning defined by law.
Although the term had a precise meaning for Shannon, in the hands of the biologists it turned into a vague metaphor, a way of thinking about something they as yet had no real understanding of: the nature of the gene.
A while later, with even less imagination, "billion" was coined, with no care being taken to give it a precise meaning, since the term today has different values in different countries.
"Philosophical terms with a precise meaning in French are turned into the opposite of what Beauvoir says," according to another contributor, Toril Moi, a professor of literature and romance studies at Duke University.
