Two target attacks from monsters

If a monster has an attack with two targets. Do I make a separate attack roll for each player, or do I make one attack roll and compare to each AC individually?

The monster in question , from A Wild Sheep Chase, has the following stat:

Whirling Greatsword Melee Weapon Attack +5 to hit, reach 5 ft. Two seperate[sic] targets. Hit: 10 [2d6+3) slashing damage.