Ukip chief Paul Nuttall twice wrongly called a female rival "Natalie" during the ITV leaders' debate on Thursday 18 May.
"I'm not Natalie, I'm Leanne," Plaid Cymru leader Leanne Wood protested to Nuttall as the pair verbally sparred over Brexit.
Nuttall, who succeeded Nigel Farage last November, made the same gaffe later during the two-hour-long live programme at MediaCityUk in Salford.
"I agree with Natalie," the Eurosceptic said as the panel discussed social care provision, while Wood quickly replied: "Will you call me Leanne?".
The Ukip leader immediately apologised for the mix-up, with Nuttall possibly confusing the Plaid Cymru chief for former Green leader Natalie Bennett.
Bennett's successor Caroline Lucas, who is also the MP candidate for Brighton Pavilion, found the incident amusing and began to laugh along with SNP leader Nicola Sturgeon.
Liberal Democrat leader Tim Farron also took part in the event, the first TV debate of the general election campaign. But Prime Minister Theresa May and Labour leader Jeremy Corbyn decided not to attend.
With three weeks to go before the 8 June vote, the latest opinion poll from YouGov, of more than 1,800 voters between 16 and 17 May, put the Conservatives on 45%, Labour on 32%, the Liberal Democrats on 8%, Ukip on 6%, the SNP on 5% and the Greens on 2%.