To win both sides of the same betting proposition; betting the favorite team at -1.5 with one bookmaker and then taking +3.5 with another bookmaker; the game ends up with the favorite winning by exactly 3 points, you have then "middled the game"; a favorite betting method of "Wise Guys".
Betting on both sides at different point spreads allowing you to win in either outcome
When you win both sides of the betting proposition.
To win both sides of a game.
Winning both sides of a betting proposition.