The film is at odds with itself as to whether this is Sarah Ann Connor or Sarah Louise Connor.
If the killing of this character is indeed the Terminator's first target (assuming he is going by the order in which they appear in the phonebook), this would be Sarah Louise Connor.
The first television report simply says that it is "Sarah Connor, 35, mother of two". But at the police station, Vukovich tells Traxler that Sarah Ann, 35-year-old secretary and mother of two, was shot six times (as shown in the earlier scene).
Then, the later television report says that Sarah Ann, 35, was killed in her apartment, and implies that the "Wrong Sarah" is Sarah Louise Connor.
Additionally, the house number of this Sarah, 14239, corresponds with none of the addresses listed in the phonebook.
If this was Sarah Ann Connor, odds are the T-800 killed her kids too as John Connor was the primary Target and he would mistake one of the two for him.