This form of subtitle spans back a long way. I don’t know just how far, but I do know that twelve of the fourteen major works by Gilbert & Sullivan had such form, beginning with “Thespis; or, The Gods Grown Old” in 1871.

Many of us have a fondness for comparatively old-fashioned approaches to various things; double titles like that are one such example, using em dashes despite space-separated en dashes being more popular is another (though that one varies by locale), and writing “&c.” for “et cetera” is another (there’s lots of fun history around the ampersand ligature).