Johann Samuel Fredrik Botha - Sources for Date of Birth

Help! Can anyone see / find where the documentation for Johann Samuel Fredrik Botha 's date of birth as 01 February 1778 comes from?

I'm trying to distinguish him from his brother: Johannes Petrus Botha
Baptism Johannes Petrus Botha 8 August1779

1779 8 Augustus
Johannes Petrus
de Vader is Samuel Fredrik Botha
de Moeder Anna Elisabeth Delport
getuigens Michiel Pens Johanna Maria Jurgens Johann Breedenkamp en Johanna Elisabeth Breedenkamp