This is mainly Roy Thomas's idea, I think (RT wrote a lot of stuff that reintroduced golden age Marvel heroes into 'modern' continuity). He wanted to explain why Captain America, Bucky, and Red Skull were active in the 50s although Stan had Captain America in the iceberg in the 40s. Hence, a 'fake' Captain America.
Funny thing is, even Amazing Spider-Man dwelved into this, during the 'robot parents' storyline:
Thing that struck me odd about that is this : The true Red Skull had files taken when he eliminated the Communist one, including the files on Peter's parents. Supposedly from hacking these, Peter learned that his parents were real. He took an enormous risk getting to these, and barely got away from Skull's forces in time. Okay. We know now that the parents were built by Chameleon and Harry in his craziest phase before his death.
Yet all that also means that Harry hacked Red Skull's files somehow and went undetected by a paranoid villain way out of his league with followers who know better than to keep such things from him. That puts Liz and Normie at risk, and however crazy Harry got, they were his first concern.
Too much speculation, I know, and I'm not demanding it be resolved. But all storylines should be thought through, and xovers, even in-universe, should be twice so.
Of course, now, no one ever knew who Peter is, and since Norman never died, Harry didn't create the androids--wow, did the Clone Saga ever take place? We know they kept the Gwen-twins.
(My head hirt now)