How do you 'deal' with other people taking photos on the day?
if it's your gear, I'd say NO.
other wise i invite them. there's no way on person can cover all the events and when I shoot wildlife sports events, i'm always curtious of other photographers.
They can shoot all day long as far as I'm concernd, but at the end of the day, it's the images that people want that sell.
If youre exclusive and paying for the shoot as the photographer, I'd say there again too, you have a right to limit who's shooting and for what reason. If others are getting in your way, and youre the "official" guy, I'd take it up with the event folks or the sanctioning body.
I dont think I'd be worried about a PS guy, they get what they get but they cant compete, I see it all the time at horse races and rodeos.
At the end of the day, i try to make friends with all the shooters around me. It's importanat to gain the respect throught both your images and your personality.
If you have an issue with people shooting, make sure it's in your contract and have the people sponsoring the event take care of the problems, that way youre not trying to enforce their rules!
Take care,