Well spotted!

You have to be quite a detective to dig into the murky past. Euphemia Dorrat certainly looks like DB's mother. I guess Euphamia or her family may have changed their surname.
When DB jnr was born, DB snr was 54 and Euphemia 30. Quite a big age gap which, given the Euphemia is subsequently living with Robert Johnston makes me wonder about the legitimacy of DB jnr. Perhaps Euphemia was a servant at Kinburn House! The double christening record for DB jnr perhaps there was some debate over the parentage.
With regard to Kinburn House, the St Andrews Museum is now housed there. I put a query in to the museum to see if they had any information about DB snr but they have not replied. Have you got any suggestions as to who I could contact in St Andrews that might be able to check out the early ownership history of the house? There are internet references to the David Buddo and architect John Milne but not to subsequent ownership prior ot the St Andrews Town Council buying it in 1920.