Well once the filling autostops you can still pour in more petrol by pressing the lever manually and it either overflows out of the tank or it is sucked back in by another line in fuel filler nozzles so this way yes you can over fill.
Happened with me once, i had to fill upto 37ltr but it stopped at 35 so the guy kept on doing that until it spill over from the tank and we couldnt reach 37 mark lol