A rewrite is always going to take less time to build than the original poorly-specified version when people were trying to figure out what to do.
And the original team could have been more junior, or if similarly-experienced than your 2-person team, adding more people to the team without good leadership can also affect productivity---or as they say in Scrum, "velocity".
And the original team could have been more junior, or if similarly-experienced than your 2-person team, adding more people to the team without good leadership can also affect productivity---or as they say in Scrum, "velocity".