Nope, parsers are perfectly in their rights to do whatever they want with multiple keys. They could read them backwards, sort them, whatever. The behaviour in the instance of multiple keys is undefined.

> This seems like a bad idea.

It is an astonishingly bad idea. I'm concerned by it being so high on the page.

> But hey, might work well for the original author.

Depends on their parser. It's undefined behaviour according to the spec. It might work now, but I'd argue it doesn't work well, as a patch level change could bork this.