Today in 1974, US Patent 3782609 A was issued, an invention of Homer R. Zucconi, for a “Keg Tapping Assembly.” Here’s the Abstract:

A keg tapping assembly comprising a tavern unit having two prongs which are sleeve-like with tapered ends to unseat the two spring closed valves of a permanently attached keg unit detachably connected to the top central hole of a keg, upon insertion into the keg unit. The invention embodies an attachment having two bores through which said prongs are detachably fitted and having serrated terminal connections onto which hoses may be slip-fitted for attachment, respectively, to a tap rod insertable in the top center opening and to a valved outlet connection at the bottom of the keg. By simply unplugging the tavern unit from the keg unit and plugging it into said attachment it is selectively usable on either a conventional single connection tap or on the older double connection tap.