I always shut both valves off when we vacate our house to ensure I don't get a continuous loss of water in the event of a burst pipe after the meter while I'm not in residence, I can only think that the rubber washers that seal the valves down have broken up as the valves open and shut OK but water still flows full bore. Earlier in the year all owners on our phase got emails to check if the valves were working, mine weren't. I routinely open and shut all the stop valves in the house and this year replaced four of them, quite a simple job.