Bennett couldn't remember Leanne Mitchell's name at all, while Linsey stumbled through a discussion about Saturday night TV, calling her "Leanne... with the beautiful, beautiful voice" to laughter from the crowd.
Mitchell has struggled to become a chart success since winning the debut series of the BBC One talent show earlier this year.
Show star Danny O'Donoghue has suggested in recent interviews that the public picked the wrong winner and that Mitchell doesn't have what it takes to become a popstar.
Syco's Head of Television Siobhan Greene told the TV Festival that The Voice UK will continue to lack credibility until it produces star acts.
"I thought the opening part of The Voice was brilliant," said Simon Cowell's colleague. "But they need to find a star. It validates the process. I'm talking about talent/punters.
"When you have a group like One Direction, who go on to become the biggest boyband in the world, it validates the show."
Watch Leanne Mitchell perform 'Who Knew' on The Voice UK below: