I have worked PT as an MT and then had an outside PT job in retail as well.
It is hard because while it equals a FT job hour wise, it feels like more (added transportation and split up shifts).
It was doable and, frankly, it was nice to get out of the house and doing something different. I personally hate the new reality of being an editor rather than an MT and cannot stand to do it for 8 straight hours a day.