Carla and Roxanna (a.k.a., Roxy) Yates, identical twins, went to high school with MacGyver, where they first met. Roxy used to try to impress MacGyver in the hopes he would ask her out; they ended up dating in high school. In her opinion “it took [MacGyver] long enough to ask me for a date”. Throughout the years, Roxy became a well known singer, while Carla a painter. Both of them enjoyed climbing, though it seemed Carla was better at it than her sister. Only Carla appeared in the episode “Two Times Trouble”, posing as herself and her sister throughout the episode.
During the only episode of their appearance, Carla created accidents in which Roxy was in danger, and, as Roxy, she stated that “my sister hates me”, making it seem the twins had developed a sibling rivalry. It isn’t discovered until the end of the episode that Roxy died in a climb with her sister two years earlier, where Roxy fell. As she was pulling her sister down, Roxy knew that Carla wouldn’t be able to pull her up and that she would only get Carla dragged down along with her. In trying to save her twin sister, Roxy took out her knife and cut the rope, falling to her death. Carla was admitted in May that same year to the Pine Valley Hospital, suffering from severe mental depression as well as a nervous breakdown. As a patient of Dr. Farrell, she also impersonated her own sister to visit herself. As MacGyver discovered, Carla wasn’t capable of accepting her sister’s death, and, therefore, brought her back the only way she knew how: by becoming her own sister.
“I loved her so much. I didn’t want her to die” – Carla “So you brought her back the only way you knew how: by becoming Roxy. But Carla, you’ve got to let her go. You’ve got to let her go.” – MacGyver
At the end of the episode, Carla wanted to commit suicide by shooting herself with a gun, but MacGyver convinced her to go back under the care of Dr. Farrell. Carla ended back into the Pine Valley Hospital, where MacGyver visited her. She told MacGyver then that she’ll always remember his smile.
“Would it help at all if I stopped by once in a while?” – MacGyver “A great deal. More than anything else, she needs a friend.” – Dr. Farrel
MacGyver stated he discovered the truth about Carla with the way "Roxy" climbed, “[she] climbed like a cat”, which he said wasn’t Roxy. Also, Carla made a painting of the last climb she made with her sister, the one in which Roxy died. MacGyver saw that Roxy was hanging with a knife ready to cut the rope, while Carla was being dragged closer to the edge, trying to pull her sister up. Finally, the fact that Roxy’s manager and that the director of a music video stated that Roxy wasn’t singing the way she used to. MacGyver proved his theory by taking the twin’s fingerprints, showing to his friend, Peter Thornton, that they were identical, and that there was only one twin impersonating the two.