Two, as logic and cliché suggest, is better than one. Hence, the Y-splitter, a not-quite-indispensable dongle that doubles any connection point. Long a tool for A/V-savvy folks, the 3.5mm (2F-1M) version often sits alongside earbuds and cases in the shelf of your local Apple store. Now comes a Kickstarter project for a product that is intended to join those ranks: the Why? cable turns one USB port into a pair of Lightning connectors (given the titular pun, we'll spare you a terrible joke about striking twice).
There are mixed reports regarding how many people/households have more than one Apple mobile device (for one thing, metrics typically include other hardware, including desktops and laptops), but it's something of a self-selecting market in the first place: Anyone who owns both an iPhone and an iPad is anecdotally more likely to buy additional accessories anyhow.