"Having got two in one hit I thought it was unusual, particularly with the times being the same and only driving the road once."
In response, police admit they got it wrong, conceding it is possible for people to be "very occasionally" fined twice for the same offence.
Police weren't able to provide any statistics to explain how often the errors happen.
The good news for Mr Piggin is that he will have to pay only one of the $30 fines. Police agreed to scrap the second ticket.
"These duplicates aren't specifically counted, so we don't have a numerical figure," said Mark Stables, manager of police's infringement bureau.
"Thank you for bringing this to our attention. These tickets relate to the same set of circumstances and we will contact the driver to advise that only the first ticket (56 km/h) is valid and the second one (55 km/h) will be withdrawn.
"This situation happens very occasionally, when a camera captures an image with the car in the middle of the frame, and again as the car nears the edge of the frame," he said.
"In this case, the car had slowed by 1km/h when the second photo was triggered. Our staff would normally pick this up and not issue the second notice."