I heard of this, years ago but in relation to bicycles. The plan is that the owner will not be able to unlock it and so leaves it, then later under cover of dark the '2nd locker' will come back and hack through the original lock at his leisure.
Can't see it happening with bikes as we've got further to go and maybe no other way of getting home, whereas bicycles in central London will be owned by people living fairly nearby, easily reached by public transport.