Hanno detto chiaramente che Cap quando torna negli anni '40 per stare con Peggy crea effettivamente una realta' alternativa diversa dalla nostra.
Cito le risposte dei Russo prese da qui
https://www.slashfilm.com/avengers-endgame-final-scene-explained/“The time travel in this movie created an alternate reality. He lived a completely different life in that world. We don’t know how exactly his life turned out, but I’d like to believe he still helped many others when they were needed in that world.”So does that mean there are two Captain America’s in that alternate timeline?
“Yes, there were two Captain Americas in that reality. It’s just like what Hulk said, what happened in the past has already happened. If you go back to past, you simply created a new reality. The characters in this movie created a new timeline when they went back to the past, but it had no effect to the prime universe. What happened in the past 22 movies was still canon.”“Both Ancient One and Hulk were right. You can’t change the future by simply going back to past. But it’s possible to create a different alternate future. It’s not butterfly effect. Every decision you made in the past could potentially create a new timeline. For example, the old Cap at the end movie, he lived his married life in a different universe from the main one. He had to make another jump back to the main universe at the end to give the shield to Sam.”
So what did Steve Rogers have to do in order to time travel back to the primary timeline and give Sam Wilson his shield? That’s a question that we may get an answer to down the road. Because apparently there are still some details Anthony & Joe Russo aren’t willing to reveal. The directors were also asked when Steve Rogers traveled back to in order to dance with her, and they said:
“We can’t answer it for now, this is a story that happened in an alternate reality. Maybe it will be revealed in the future.”