Ok, how about this for an idea. We take it in turns to post a favourite (British spelling) comic cover every day. This went really well on the comic fan website that I used to frequent. What we tried to do was find a theme or subject and follow that, until we all got bored with that theme. I'd like to propose a theme of letters of the alphabet. So, for the remainder of October (only 5 days) and all of November, we post comic cover pictures associated with the letter "A". Then in December, we post covers pertaining to the letter "B". The association to the letter can be as tenuous as you want it to be. For example I could post a cover from "Adventure Comics" or "Amazing Spider Man". However Spider Man covers can also be posted when we're on the letter "S". Adventure Comic covers could also be posted when we're on the letter "L" if they depict the Legion of Super Heroes. So, no real hard, fast rules - in fact the cleverer the interpretation of the letter, the better, as far as I'm concerned.
And it's not written in stone that we have to post a cover every day. There may be some days when no cover gets posted. There's nothing wrong with this, it just demonstrates that we all have lives to lead.
If everyone's in agreement I'd like to kick this off with one of my favourite Action Comic covers, from January 1967. Curt Swan really excelled himself here.
Do the covers have to include the doppelgänger and the original?
All the covers that I'm planning to use show at least two images of the character who's been doppelgängered. I'd suggest that, if a cover shows only one image of the character (or if they're not obviously doubles), you should explain why it fits into this theme.
Here's a cover where the reason for it being included should be self-evident. Animal Man, who can mimic animal powers, copies the replication abilities of bacteria.
At times, Superman has had more than copies of himself to deal with.
The lead story was produced just as National/DC acquired ownership of the Fawcett properties, for Superman's opponent (Captain Thunder) is a doppelgänger of Captain Marvel, now reduced to being known as Shazam. This is the only Thunder appearance (complete with kid secret identity) I'm aware of, for the dimensionally lost superhero was on his way home at the end of the story.
Ironic in hindsight, considering at least part of the reason Fawcett eventually went out of business was National's long term lawsuit against them, claiming Captain Marvel was a Superman rip off.
(Image courtesy of the Grand Comics Database)
Re Superman #276, DC didn't bring Fawcett characters into the DCU, on an alternative Earth, until the JLA/JSA crossover in Justice League of America #135-#137, contemporary with Shazam #26 (when Joe Orlando took over as editor and the title got a makeover). Lex Luthor had met Captain Marvel in Shazam! #15, contemporary with Superman #281, but he was taken there by the discharge from a magic accumulator he'd invented, and the implication was CM's world was a magic-verse or didn't really exist. That story and the one in Superman #276 were both written by Elliot S. Maggin, who wrote a fair bit for Shazam! while Julie Schwartz edited. Note the Monster League of Evil in the Superman story, made up of real monsters.
Fawcett had intended to call CM Captain Thunder, but the name was already in use at Fiction House: a French Foreign Legionnaire hero, Captain Terry Thunder, was appearing in Jungle Comics. In his introduction to the Shazam! from the 30's to the 70's collection E. Nelson Bridwell pointed out a series of references to Fawcett's founding title, Captain Billy's Whiz-Bang: Captain Marvel, Billy Batson, Whiz Comics. He implied the magic bolts were a reference too, observing they normally went "boom" instead of "bang".
Some of the character names in the Shazam! movie were references to people who worked on the Golden Age feature.