The Missile Men created evil duplicates of the Metal Men (this seems to happen a lot), but they didn’t make the cover.
Doc Magnus creates another set of robots with similar properties to the original Metal Men (Silver, Cobalt, Osmium, Zinc, Gallium, and Iridia [iridium]), unfortunately, they become possessed by an “evil living intelligence.”
And how should we deal with the Squadron Sinister who were duplicates of the JLA?
Gotta say, just from the cover image, looks like the then new Avengers are going to get creamed by the original team. Hank might do ok against his alternate self and Hawkeye might hold his own against Iron Man, but the chances of Cap beating Thor or of T'Challa beating the Hulk seem pretty slim. And notice, Roy the Boy brought back the Big Three plus the Clint version of Goliath to take on the Big Four JLA doppelgangers. The odds looked quite a bit more even for that cover scene.
Hoy Murphy said:
Any other Silver Age teams have evil counterparts with essentially the same powers?
Surely that can never have happened!
Actually, I remember this Legion tale. It features six teens who have the same powers as six members of the Legion, because they come from the same planets. The applicants claimed that the Legion's "no duplicated powers (except for Superboy & Supergirl, because they're special)" rule was unfair, and challenged their counterparts to fight for the right to remain members. After (spoiler alert!) they lost, some of the applicants went on to join the Legion of Super-Villains.