Double betting is essentially to give you a greater chance of winning from a single event. In football, it can be used to cover two of the three possible outcomes in a single bet. It combines a win/draw for both sides, or the option to get rid of a draw entirely.
Double betting can be a great way to win when looking at a game between two open teams. For example, you can bet on a game between two teams that score and concede a lot, but have few draws so a double chance bet on the home and away team is suitable for this situation. It’s also a great way to bet when backing a team that is expected to win, because in case they make a mistake or struggle to score, the draw option is still covered and you’ll win on that particular selection.