I mean that if you have different horses for various offers in the same race - each horse will balance against each other at the exchange and reduce the overall liability needed at the exchange.
For example, an 6 runner race if you had for each bookie in 1 race:
- Bet365 - Mauve Rum,
- Skybet - Blue Road
- Betfair sportsbook - Purple Reptile
- William Hill - Orange Person
- Coral - Yellow flo
- Paddy - Green graze
All the lays would balance against each other, so the total liability would be less than if you just layed 1 horse in a particular race.