Maybe possible, but I think it would take a driver
delibrately "riding" the brakes with just the right pressure so the car doesn't slow down too much. And it would take a long time, maybe tens of seconds, or minutes. It makes no sense when you can stop the car in seconds with the same brakes.
I don't doubt unintended acceleration happens. The thottle can get stuck open, computer malfunction, etc. But it's a one in millions possiblity. What are the odds of brake failure happening at the very same time? That's what I don't believe.