According to neighbor Bissey, they are supposed to have arrived separately - 30 minutes apart. That means one car per stripper. Simple- Kim drove to the house, the accuser was dropped off later on by someone (boyfriend?) Afterward, both strippers left in Kim's car.
OK - if Mangum were dropped off and things had gone off without incident, how was Mangum supposed to get home? Call someone to come get her at 2 am? Either Mangum had prearranged with Kim, who Mangum was not supposed to know before, or someone else (boyfriend/pimp) was to be called out. Maybe Mangum's really stupid, but I sure wouldn't go out on an assignment like that one unless I knew I could make a quick exit if I had to.
I'll bet Mangum's cell phone (recovered with her purse?) and the record of calls has a wealth of information about her activities that evening.