Barbara series

From Memory Alpha, the free Star Trek reference.

The Barbara series was a group of 500 identical androids who inhabited the planet Mudd. They were designed according to the personal specifications of Harry Mudd. (TOS: "I, Mudd")

The Barbara series was used as a model to describe to the crew of the USS Enterprise some of the engineering specifications of the Mudd androids. Covered with a self-renewing plastic over a skeleton of beryllium-titanium alloy, the duration of this model was estimated at 500,000 years.

The Barbara series was played by twin sisters Colleen and Morreen Thornton.