Dueling legislative proposals in Virginia backed by different gambling companies would open the door for an expansion of slot-like betting machines in businesses such as truck stops, restaurants and convenience stores. For years, the machines have proliferated as policymakers grapple with how to regulate them amid a big-money lobbying fight featuring stiff casino industry opposition to the devices, also known as skill games. Virginia is not the only state grappling with skill games, but the efforts there reflect points in a larger debate nationwide as they have exploded in popularity.