it becomes a win double or e/w double so the fact your first horse lost brings the whole bet down.
Yes, otherwise you'd have punters whose horses in the 2.30 and 3.00 came nowhere, but who go back to the bookies to get their money back when their runner in the 5.00 is withdrawn, which is clearly insane.
famous scam from a few years ago, using multiple bets to disguise big bets for single horses, by the legendary Tony Collins :
Collins had also entered two other horses, Opera Cloak and Ankerwyke, in races at other courses.
A vast number of small bets were laid, backing Gay Future for a double with either of the other two horses.
Both Opera Cloak and Ankerwyke were pulled out of their races, the double now became a single and, hence, a lot of money was riding on Gay Future.
Soapy flakes were then rubbed into the legs of the Gay Future to give the impression the horse was sweating and keep on-track punters from backing it, holding its odds of 10-1.
The horse duly romped home in first and, following an investigation, Collins and an Irish building contractor Tony Murphy were convicted of conspiracy to defraud the bookmakers and fined.