A Bit of History, or the Principles of Creating Dual Titles Outlined in Their Chronology, by Cloudchaser
Ancient and medieval texts did not usually have a title. The titles by which we know ancient texts today were mostly given to them by later copyists or librarians (e.g. the Metaphysics are those books by Aristotle that were placed "behind" (gr. meta) the books on physics by Andronicus in his edition of Aristotle's works). Medieval texts either had a brief passage either at their beginning (incipit) or end (colophon) which gave the author of the text and briefly summarized its content.
For example, the incipit to the Liber Scintillarum reads:
Incipit liber scintillarum, id est diversarum sententiarum, distinctus per LXXXI capitula. [Here begins the book of sparks, that is a collection of moral sayings, divided into 81 chapters.]
In this example we can already recognize the structure that is the topic of this question: a name ("book of sparks"), an explanation ("that is ..."), and further information about the book.
After book printing had been inventend in the 15th century and books were no longer handcopied for a known client (who didn't have to be swayed to buy the book), but published in numbers for an anonymous audience who had to decide which books they wanted to buy, books were given a title page which had an advertising function similar to that of book covers of today.
Until the 16th century, the text on those title pages was usually not chosen by the author of the book, but by its publisher, who used certain conventional forms to attract buyers by promising, in case of a novel, "a pleasant diversion", "useful and edifying", and based on "true events".
Here is a typical example of such a title page (click image to view a large version):
This translates as:
Necessary inventory of the history of German dramatic poetry, or a catalogue of all German tragedies, comedies, and musical comedies which have been published in print between from 1450 until the first half of the present century, collected and brought to light by Johann Christoph Gottsched
Instead of the id est, "that is", of the medieval Latin text, this example already features the "or" that is so common in titles of the 19th century.
But in this example, the two parts of the "title" aren't a name of the book plus an explanation, as in the medieval example, but rather two different explanations of the content of the book ("inventory of dramatic poetry" and "catalogue of tragedies etc."). Some books from that time have a title that juxtaposes two synonyms:
Dictionarius vel Vocabularius Germanicus diversis Linguis respondens [Dictionary or vocabulary of diverse Germanic languages]
Providing synonyms for many words was a common practice at that time in text, too. In the 15th century, most European languages were still divided into mutually unintelligible dialects, and a common lingua franca (such as High German or Early Modern English) were only just developing. Many dialects not only differed from each other in phonetics and grammar, but also had different words for the same thing. When an author wanted to write in the evolving common language, they often used two synonymous words from different dialects to ensure that their readers knew at least one of them.
From the 18th century onwards, books were increasingly reviewed in literary magazines, and the synopsis of the book's content on its title page was no longer necessary. As a consequence, titles became both shorter and more grandiloquent and contrived, employing methaphor and allegory instead of directly stating what the book was about. This tendency was criticized by art critics of the time, but widespread nonetheless.
But not all Victorian book titles are "dual" titles or stilted. Vanity Fair, Middlemarch, or The Importance of Being Earnest – to name just a few – do not follow the principles outlined above.
Most of the information in this post is taken from:
Erchinger, P. (2009). Titel. In G. Ueding (ed.), Historisches Wörterbuch der Rhetorik (vol. 9, pp. 581-590). Darmstadt: Wissenschaftliche Buchgesellschaft.