A brief reflection of light made some players think an Irish lottery winning ball had two different numbers on it, chiefs said.
The National Lottery assured its players of the integrity of Saturday night's Lotto Plus 1 draw.
A statement said: "A brief reflection of light during filming caused an illusion and some players to think there were two numbers on ball 38. This was not the case.
"The weight and size of all Lotto balls, and the numbers, are strictly checked in advance of each draw.
"This process, as well as the draw itself, is independently observed by our auditors KPMG."
A picture shared on Facebook earlier appeared to show the number 38 ball also had the number 33 on it when it was drawn in the Irish National Lottery last night.
It drew some commentary on social media.