A "CAPTCHA" option when booking courts

Call me crazy but we suspect that some members of our club, who work in IT have developed a simple software which allows them to quickly reserve courts at the moment they become availible (we suspect this based on the speed in which courts are being reserved and at the frequency of the courts being reserved by certain members ((less then 4 seconds)). Having a simple option to enable a "human" test would resolve this potential issue. However, I understand this is not a concern for most clubs! 

PS- this is actually a big issue with our governing body and tournament sign up as well, crazy stuff.