'The Flying Nun'
'The Six Million Dollar Man' - "Little Orphan Airplane"
'The Rockford Files' - "The Battle-Ax And The Exploding Cigar"
Marge Redmond played all three roles. Originally I had Sisters Jacqueline and Annette as actual sisters as well as "sisters". But Caeric ArcLight informs me that not only did Sister Annette have an accent, but that they stated they were not from America. I could have splained my way around the accent - too long among the Kataran population - but being non-American. Still, if Corporal Randolph Agarn could have identical-looking family members from all over the world.....
* Most online sites have her name listed as "Annett", while the show's wikia had it as "Anneti". But a DVD frame grab supplied by Caeric ArcLight had a caption that listed it as I would expect it to be spelled - "Annette".
My thanks to fellow Crossoverist Caeric ArcLight for all of his help on this post. Without his help, I never would have known about Sister Annette......