As dschleef said, the epoch span is one day. You will notice that dist_1_v1 is less than dist_0_v1. This fixes the problem you noticed, leading to a reasonably

As dschleef said, the epoch span is one day. You will notice that dist_1_v1 is less than dist_0_v1. This fixes the problem you noticed, leading to a reasonably correct, shrinking value for the distance between Voyager and the Earth.