Possibly a transcription error repeating the daughter's name or slipping a line.
By the way, if you know the IGI batch number (e.g. the number for St Matthew christenings is C038041 - the full list of batch numbers is on Frances's site), by typing in the batch number and a parents name(s) you can find the all the children christened in that parish with that parent.
For example if you enter Carron in the mother's last name box and C038041 in the batch number box, you wil find 35 christenings in the Parish with a mother's maiden name of Carron, or a variant thereof,
including that of Elizabeth Faill.