Andrew Ashley, 30, and Nimesh Bhagat, 31, stole more than £33,000 by infiltrating software controlling remote betting machines covering live roulette wheels at four Gala Casinos in London, a court heard.
The pair simply made the machines print out winning vouchers for sums of up to £600, whatever the outcome on the wheel.
But they were caught out when a cashier realised a payout was impossible as only £10 had been wagered at odds of 35-1, Croydon Crown Court was told.
Officials began an inquiry and quickly traced a string of suspicious wins back to the two contractors, who were employed as problem analysts.
Ashley, from south-east London, and Bhagat, from south-west London, were handed 12-month prison sentences, suspended for two years, after each admitting an offence under the Theft Act 1968.
The two men were ordered to undertake 200 hours of community service and pay back around £16,000 each, a police spokesman said.
The convictions are believed to be the first where people have been caught mishandling the computer technology behind Britain's gaming industry.[...]
Detectives examined computers seized from the men's homes and looked at CCTV footage that placed the men at the terminals when the offences occurred.
Detective Inspector Ann-Marie Waller said vigilant staff stopped the fraud before hundreds of thousands of pounds were lost.