Several ideas have been submitted, these include:

• When one player finishes, the other player is kicked to lobby (simulated by leaving)
• Player's can wager an economy amount, for example "/pa challenge (player) 100". For safety this could be processed when a player actually completes the course, for example reduce the loser by (amount) and increase the user by (amount).
• Broadcast a message when a player beats the player "(player) beat (player) at (course)!"

"/pa challenge (course) (player) [wager]" has been added
Challenges now live until a player quits or completes the course, each player will be told if they won / lost and will recieve or deduct the wager. The loser will be kicked from the course.