In the Spurs game, however, Tyler Herro subbed in for Kyle Lowry both times and handled PG duties even with Gabe Vincent on the floor.
Not only that, but Herro and Lowry did see time on the court together in that game and Herro was still tasked with playmaking.
Spoiler:
Judging from what I've seen, Herro's not ready to be a PG in the playoffs, so I doubt it stays this way, but it is interesting that Spo has kept him at PG even after Lowry returned - even more so with Lowry and Herro on the court, at least as far as playmaking goes.
My theory is that Spo wants him to work on making his teammates better and improving his handles. In that sense, I think this is a good role for him because the hallmark of any great player is making their teammates better and they're also expected to handle the ball in pressure situations.
Either way, I think the return of Oladipo should answer once and for all as to whether Herro remains in the backup PG role.