The most likely outcome in this scenario, where two identical cars are rolling down identical hills and then roll on identical ground, is:
The two cars will roll forward, eventually both coming to a stop at the same time due to friction.
This is because both cars are on the same type of ground with identical conditions regarding friction, and since they are identical in size and shape, they will experience the same forces acting on them. Therefore, they should both come to a stop at roughly the same time due to the effects of friction acting equally on both cars.