D80, The olive house snake and the brown house snake are two different species. In fact there are four species of house snakes indigenous to South Africa that I know of:
Lamprophis Fugilinoses (I keep wanting to type "fugli noses) - Common Brown house snake, that you call the African Brown house snake.
Lamprophis Capensis - Cape house snake
Lamprophis Aurora - Aurora house snake
Lamprophis Olivaceus - Olive house snake
There are a few other species indigenous to Africa but not to South Africa itself.
My little one is either a very dark L.Fugilinoses (Brown house) or a cape house snake...I am currently doing research and trying to find out how to tell the difference.

Will let you guys know what I find out!