The family is on a 10-day royal tour and during this special outing with their son, they all met with anti-apartheid activist Archbishop Desmond Tutu and his daughter, Thandeka Tutu-Gxashe.
During the visit, the Duchess of Sussex revealed her special nickname for her son -- "Bubba."
In a video of the couple arriving, Markle can be heard saying “Oh, Bubba!” as she carries him into the building.
Archie looked adorable in a white long-sleeve shirt and blue striped overalls and fans on social media couldn't help but point out the uncanny resemblance between the baby and the Duke of Sussex.
"#archieharrison is his father's twin," wrote an excited fan.
"The resemblance is out of this world," said another.
One person even got confused over the photos -- “Thought these pictures were of the same child!!”
Archie, born in May, is the first child of Prince Harry and Meghan Markle and seventh in line to the British throne. He was christened in July.
Prince Harry and Markle's tour started on Monday and later he will head to Botswana, Angola, and Malawi with a special focus on wildlife protection.
While the Duke is traveling, the Duchess will remain in South Africa, with events there including a Johannesburg visit to a charity that helps to raise awareness of sexual violence in schools.
The royal family's Africa visit ends on Oct. 2.
The Associated Press contributed to this report.