When Rimmer needed to identify an antivirus to the chameleonic microbe eating Red Dwarf, he crossed into a mirror universe where everything was opposite. Heading to the science labs, he found a woman who looked almost identical to Kochanski . Assuming that she would be as intelligent as her counterpart, he asked her to identify the antidote.
This version of Kochanski had long blond hair and wore much more revealing clothes. She was uninterested in Rimmer's problem, describing it as "brainbox-type stuff", and seemed more intent on filing her nails. The real intellectual was The Professor, who resembled The Cat in a total reversal of their roles on the original ship. ("Only the Good...")
Behind the scenes
In lines that were cut from the televised version of "Only the Good...", Kochanski's duplicate is much more disdainful of Rimmer's authority. She explained that she didn't have to work aboard Red Dwarf, because she was trained to work in a cake shop.
Chloë Annett's scenes were reshot after the first version of this character was deemed to be unsatisfactory. The character in the original script looked the same but was much less harsh and more stupid and giggly, coming across as a harmless idiot. Both this scene and the lines cut from the show can be found on the DVD of series VIII.