It happens, not frequently but even once in a blue moon it's enough. I had such an issue once in T3 when flying standby; thankfully I always check my BP and I saw that I was given the BP of a lady (I'm a man). Returned to the desk and got the right one. I checked afterwards and the guy at the desk, who clearly would've loved to be anywhere but there, had simply checked in the first person in the list of the standbys. I was the second.

It was the only time I raised this with management but it shouldn't ever, ever, happen.