Yes, it is. When I was about 10, we had neighbours whose daughter and I used to play together. Her mother was Catherina, and I called her Tannie Cato, which did indeed sound like cahTOOah. The Latin author is CAHtooah.
It's impossible to tell, but Afrikaans seems to have originated from as many Dutch dialects as there were Dutch settlers/sailors who lived here from 1652 onwards. There was a mixture of dialectal forms, and also a lot of simplification (we only have die as the definite article; het disappeared) to make communication with each other and with imported slaves and local indigenous people easier.