A 1-way move is basically not a move that involves traveling back and forth. It involves loading all of your belongings into a 1-way moving truck rental or having labor-only movers to load them for you and setting them up somewhere else.
Going back to the former home is not involved here. The 1-way move is usually a long-distance move. During an in-town move, your return miles are included in your moving costs. However, 1-way truck rental is not like that.
The cost of your truck rental is determined by the weight of your loaded rental truck and the distance involved in your travel.