Trevor Noah becomes Ben Carson's 'evil twin' — and mocks him to his face
Ben Carson competes against 'Ken Carson' on 'The Daily Show' on April 19, 2016. (YouTube)

Former GOP presidential candidate Ben Carson took part in a debate on Tuesday's Daily Show. Not against another political figure, but against "estranged identical twin brother" Ken Carson.

Donning a fake mustache and beard, host Trevor Noah took the opportunity to revisit his impersonation of the former Johns Hopkins neurosurgeon, complete with awkward pauses.

"Excuse me, I would like a chance to answer this question," "Ken" interjected early on, only to stand there swaying, explaining, "Sorry, I was blinking. What were we talking about?"

Prodded back on topic by moderator Desi Lydic, he said, "Four years is not very long at all -- it's barely enough time for me to count to ten."

Ben Carson then revisited his infamous remarks comparing the Affordable Care Act -- aka Obamacare -- to slavery, arguing that he made them before learning that "if you say things in a certain way, people can't hear what you're saying."

"I believe Obamacare is much worse than slavery," Ken countered. "At least under slavery, if you liked your slave you could keep your slave."

Watch the debate, as posted online, below.