If they had spent another buck for a powerplay they would have won $600000 each.
There was a similar incident a couple of years ago in Colorado. A convenience store clerk also made two copies of the winning lottery ticket. The original buyer refused to pay for the extra ticket so the clerk kept the ticket. There was no hugs down at the lottery commission because the original buyer had to split millions with the clerk. Serves them right for being a jerk. If a clerk had made a mistake and produced two tickets I would have bought both of them in a heartbeat. I would have known the clerk would have to make up for the extra ticket out of her own pocket.