Karen 2 was a computer that Plankton built to replace the first Karen in the episode Karen 2.0. She is also the main antagonist of that episode. She is only seen in the episode Karen 2.0 because she explodes at the end of the episode.
Karen 2 is more evil and also has a different design from the first one. Unlike Karen Classic, she did not have arms (even though she used a utility arm to access the Chum Bucket power grid). She was destroyed by Karen Classic at the end of the episode when. Karen destroyed her because she ran over Plankton by accident because she wasn't paying attention where she was going, and because Karen smacked Karen 2 in the screen (face). She was going to have arms but they were never included.
She was rebuilt (sort of) by taking off the glass and electronics out of her screen and Mr. Krabs put it on Squidward's face to help bring in more customers (Mr. Krabs says the kids love robots). Squidward said: "Hello, welcome to the Krusty Krab. May I take your order? Beep beep..." He also mentioned he wouldn't mind to have his face in the toilet.
Many people would say that Karen 2 and Karen could be sisters, though, this is unconfirmed.
However, Plankton created them both, so this could be fact.