What you suggested seems likely. When I drove for both, I would try to remember to turn the other app off when I had a rider (maybe turn it on when I was a few blocks from my destination). Because of how the apps worked, it was much easier to forget to turn Lyft off. But if I got a request while I still had a passenger, I'd decline it. I would NEVER start a ride unless I was at the pickup point and generally not until they were in the car, or I had at least made confirmed eye contact. It's possible a car can seem to wander around if the roads are complex or the driver gets lost.