DC's multiple Earths get blown out of proportion by Marvelites. There was Earth-2, yes, and then Earth-3, the villainous Earth. After those came a tale of Earth-A which was an alternate timeline construction of Johnny Thunder's Thunderbolt under the command of the criminal Earth-1 Johnny. That Earth vanished at the end of the story. There was a Mirror-Earth in the Flash which was only visited twice that I know of and then, sadly, the bordering-on-unprofessional Earth-Prime, where DC staffers could interact with the DC characters. 

Earth-S came about to accommodate the Fawcett characters and their unique, more light-hearted worldview. Then, Earth-X was invented for the then-recently-acquired Quality Comics. Earth-B was a never-acknowledged-on-panel letters column joke and Earths-C and C-Minus were ho-ho-ho-stop-it-Roy-my-sides-are-aching, self-impressed yukfests from a defecting Marvel staffer havin' a bit of fun at his new employer's expense. 

At worst, that brought us up to nine extant alternate worlds by the time of Crisis, none of which caused any storytelling problems to the rest of the books unless a story happened to be set directly on one of them. And even then, the explanation for what was occurring was right there on panel every issue. No muss, no fuss. No real confusion, except perhaps for Marv Wolfman, who just didn't seem capable of wrapping his head around all that. 

Most of the parallel worlds featured unique characters with unique characteristics. Uncle Sam and co. on Earth-X had no counterparts except for Plastic Man and that's not too confusing, but maybe it is for some. Earth-S's Marvel Family had a couple of Earth-1 counterparts who appeared just once. Too confusing? I don't see how, but hey, maybe some folks are just not up to the challenge... There's an Eighties-era Earth-1 Julius Schwartz who showed up exactly once, but for the most part, DC parallel Earths did not contain lookalike counterparts, the way, say, nearly every issue of "What If" did, with Galactii, Cosmic Cubes, and Serpent Crowns multiplying alongside them.

Meanwhile, Marvel began to gorge itself on "alternate timelines" and futures where representatives came back to the original. Sales events began to build around new ones forming, many that were close to, but not quite, versions of previously established futures, and the counterparts began piling up at a precipitous rate. Then the comic Exiles came along, every issue set upon an ever-expanding list of parallel realities with new and different Sue Storms and Nightcrawlers and Blinks and Wolverines... Cross-Time Councils of Kangs and Legions of Infinite Reed Richards began to glut the titles... Cue the Ultimate Universe...

It is disingenuous to pretend that DC somehow has a weakness for this storytelling construct that Marvel wisely rises above. Yeah, for maybe the first ten years Marvel avoided these pitfalls, but then, so did DC for it's first ten or fifteen. Sadly, since Crisis, the very thing designed to clear up the problem, their indulgences have most assuredly sunk to the depths of Marvel's post-DOFP "Crisis of Infinite Timelines" w-w-wackiness. 

How far do Marvel's depredations continue to go along these lines? I know that Marvel catalogers, especially those of the online variety, cannot get enough of them. It's very au courant to cite every possible variation of Marvel's IPs as a separate earth. Gaiman's 1602 is one. Earth-X is another, maybe a number of others. Nicholas Hammond's Peter Parker has his own no doubt. Anyone here see the animated "Spider-Man and His Amazing Friends" show on Saturday Mornings in the Eighties? No doubt you'll be tickled to learn that they were all massacred during one of Dan Slott's "Crisis of Infinite Spider-Men" storylines from a short time ago. Even Ms. Lion's bloody corpse was shown on-panel! Ho-ho! Such fun! I wonder if Aunt May's murdered body was just downstairs! Wouldn't that just be a riot?

Now, of course, if you want, you can always just presume that in some other timeline on that parallel Earth, everyone survived, but that would technically give you yet another parallel Earth with lookalike counterparts...

Here's a story from PHANTOM STRANGER #15 (Oct., 1971), written by none other than New X-Men creator Len Wein and featuring an African woman named Ororo!  (She's a doctor/scientist type here but, you know, the Multiverse and everything!  Probably dyes her hair.)  Jim Aparo drew the story, but I guess that's supposed to be her on the cover too, drawn by famed X-MEN artist Neal Adams--so he technically gave us the first view of Ororo.  Two X-MEN legends gave us an Ororo at DC four years before Marvel did.

I just preferred the shared earth approach. I loved it when Spider-Man showed up in a TRANSFORMERS comic (or was it the Transformers showing up in a SPIDER-MAN comic?). Wow, these guys live on the same earth. 

Having some book/person later designate it as having occurred on Earth-246534 is, well, what's the point?

It was OK in Captain Britain but did not need to become such a mill stone around Marvel. I really don't understand why they do these things. Kids just don't care about them.

Talk about sucking the fun out of it all; talk about treating the comic universe like some science project where every jar has to have a designated set of numbers/letters; and talk about missing the point.

That guy could never resist tinkering. You could buy him a near-perfect car and he'd have everything changed. It's a shame an editor or senior person didn't say no to such indulgences.