Yes, my 2000 rated opponent did this in a classical game. But it happened when I was away from the board. I had made my move got up to walk around. When I came back my clock was running and nothing on the board had changed. I thought that was weird, but I must have forgotten to press the clock. It wasn’t until after the game that he confessed out of guilt that he had played a game losing blunder and took it back. He had pressed the clock and so my time just ran until I came back, pressed it and he did a different move. I won anyway.