Can someone please explain to me the workings of all-up bets. It said on the back of the betting slip that you made two or more bets and the winnings of the first win rolled over and funded the next bet. I must have misunderstood though because why not just do two normal bets on the two seperate races?

E.g
The way i understand it now is as follows:
All-up
Race 1: Number 1 (win) - $5
into
Race 2: Number 1 (win) - $5

Race1: Number 1 ends up winning and pays $5
So $25 rolls in to fund the second bet which also wins paying $5.

Why not just go and place a 5 dollar win bet on race 1 number 1 and a 5 dollar win bet on race 2 number 1?

Cheers