new abn for new business ?

i currently have an abn for my current job as a contractor. If i decide to start a second business in a different industry to the first one, do i need another abn or just use the same one ?
we had 4 businesses all operating under the one ABN. If you have separate ones, I think you would need to do accounting/ GST etc for each one. So, I think its something you'd want to avoid,

We had the one company, but two trading names, ATO gave us one ABN but under Branch 1 and Branch 2.

We had to do two BAS and just ended up being a real pain, so we now operate under the one name.

Keeps it simple, plus only one BAS!!