They added: “This ‘new’ Marty, or Marty 2 grows up in the newly altered timeline that, luckily, isn’t altered enough to prevent him from meeting Emmett and thus, allowing him to go back in time.
“So Marty 2 goes back in time on the same night Marty 1 did and winds up being witnessed by Marty 1 that same night.”
In the comments, another fan questioned if a new timeline would always be created.
Reddit user SpideyFan914 wrote: “So what happens to Marty 2 anyway? He gonna alter the timeline even further and wind up a whole new timeline 3?”