This is a theme we used to see all the time in superhero books - a real hook to grab the browser's attention. Of course, it normally turned out to a crook in disguise or a dream but they're still a lot of fun. Let's take a peak at a few of them:
I been reading the Adam Strange Archives, and this cover from Mystery in Space #59 jumped out at me. I don't think that I'd ever taken note of it before. It's another stylish Adam Strange cover (there are so many beautifully designed covers from that series) and the Giant Adam vs. Mini Adam battle looks to be a good one. I haven't read the "Duel of the Two Adam Stranges" yet, but I imagine a rogue hypernuclear Zeta beam is involved. I've really been enjoying these early Silver Age stories - Gardner Fox wasn't perfect by any means, but he certainly had a vivid imagination.
Captain America's backstory is enough to give anyone a headache as he's been frozen in ice, lost a sidekick, hooked up with a daugher of one of his contemporaries and had some weird 50s replacement retconned into the system. It only makes sense, then, that he should eventually have to duke it out with himself at some point, as shown on the cover to Captain America #156. I can't recall ever having read this book, but I imagine that it really comes down to sidekick vs. sidekick. My money's on the Falcon, especially if Red Wing gets involved.
Ok, ok - I know this isn't really a second Wonder Woman, as the cover clearly states that it's a robot (I wish they had spoiler alerts back then), but it's still a very, very stylish cover. I think that the cover to Wonder Woman#48 was drawn by Irv Novick - who contributed some very nice Wonder Woman covers in the early 50s, while HG Peter was still doing interior work. This cover acted as a nice springboard for a lot of the kooky WW vs. WW covers later produced by Andru and Esposito (see #84, #98, #111 among others - and there are plenty!). When did they stop making explosive in that format?
Gene Colan got in the act in the late 70s with this cover to Daredevil #156. If memory serves, this one falls into the 'hallucination' category, as DD's in a coma or something rather. What I like about this one is that not only is Red DD fighting Yellow DD in the ring, but Matt Murdock is there too, acting as someone's trainer - or perhaps for both of them. I cannot remember how this one ends, but I imagine that DD wakes up from the coma and feels a deep sense of satisfaction that he changed to the red costume so early in his career.