I'm conflicted about this. Being able to use two versions of React on the same page has a very obvious practical benefit for developers, but <i>man</i> does it feel like bad practise. Yet more JS dependencies you're forcing users to download and parse before your site is usable.<p>I guess the overall argument with React and download/parse times is long since resolved (broadly, people don't care, those that do use Preact or similar) but for me personally it still feels like a downer for the industry at large.