An interesting situation where a punter can potentially cover their bets by placing another bet. For example, if two horses in a race are clearly favourites to win, and they are both placed at high odds, the punter can bet on both and still win.
This is a form of laying off (which basically means lessening risk and maximising potential returns), and though you will not win as much as with a single bet, if your judgment about the horses' chances are correct, you will still show a profit with much less risk.
For example, two horses at 3-1 and 4-1 are clear favourites. The punter may lay a bet of £100 on each, confident that whichever wins, they will still show a profit (outlay of £200, total winnings of either £300 or £400).