TIL several first authors

I was just informed by my colleague that the point of several “first” authors – which is in practice (in our field) used in publication lists to show who has done the most work – is that I could switch the first names in my publication list / resume (perhaps with a note explaining this so that people searching for it don’t get confused) to show that I’m a first author as well. Is this a thing? I’ve never heard of it, but I’ve never understood the point of several first authors either, and this would explain the sense in it. Do people do this?