If a player rolls doubles, the player may move the number rolled on the die 4 times. For example, if a player rolls double 3's, that player may move his/her checkers 3 points 4 times. The player may move up to 4 different checkers in order to complete the roll. However, the player may opt to use 1 checker if need be.
In the image below, the player (white checkers) has rolled a double 3. This player may move their checkers 3 points 4 times. Below is an example of where to move. The player would move two white checkers from the top right quadrant into the slot with the arrows, and 2 checkers in the bottom left quadrant over 3 points.