A COMPUTER glitch could see a lottery company forced to pay out $19.6 million ($A25.1 million) in prize money after duplicate winning tickets were generated for two hours.

The programming glitch in South Carolina, US, created winning "add a play" tickets on Christmas Day, with each having a prize of $500 ($A640).

After noticing the error, Nicole Coggins and her mother-in-law, Shawanna Ladd, bought $100 ($A128) worth of tickets at multiple locations - a move that resulted in them winning $18,000 ($A23,000).

"I played $10 first, and I won on every ticket," she told WYFF News 4. "So I thought, 'Well, maybe there is something wrong with their machine. This can't be real.'"

It turned out her inkling was correct, because when she went to collect their winnings, the machine said their tickets were invalid.

The South Carolina Education Lottery addressed the issue with a statement.

"From 5:51pm to 7:53pm, the same play symbol was repeated in all nine available play areas on tickets which would result in a top prize of $500," it wrote.

"No more than five identical play symbols should appear for a single play. As soon as the issue was identified, the Add-A-Play game was suspended immediately to conduct a thorough investigation.

"All players who purchased a Holiday Cash Add-A-Play ticket on Christmas Day during the time period affected are advised to hold on to their ticket(s) until the review is completed."

In a later statement, the company said there would be a meeting before the end of January to discuss the outcome, but would set aside the millions needed to give winners if it was required to validate the tickets.