I don’t think Simon ever won the coin toss as he and Catherine had him believe. There was never a coin toss to be made for having his consciousness be transferred to the desired host.
The game placed you in the new version of Simon to set you up to think this way, and it worked. This is just another addition to the gripping ending.
The realisation that the older Simon was deceived by Catherine, or she was simply unaware herself. Simon 2 never made it into Simon 3, it just felt that way.
The third copy of Simon obtained all of his experiences and because of this, truly believed he was still the consciousness of Simon 2.
Truly remarkable how hauntingly good this narrative is.