I've had good luck so far the two times I hired a duo. My apartment building has a doorbell camera -if I'm hosting I use that as my first screening process to determine the person arriving is who I am expecting, and noone else if hiring a single person.
Worse experience was traveling to a hotel to meet a provider and finding they had 3 "friends" in the room, likely to rob me or worse. I got out of dodge right quick!