Thirty-five-year-old George Crute III, is suing officials at the Federal Correctional Institution-Loretto over the Feb. 5 incident.
Crute says he wrongly lost his "good conduct" time that would have shortened his sentence and his job as a clerk.
Prison officials contend Crute took the sandwiches out of the machine.
The Tribune-Democrat of Johnstown says a guard claims Crute ran away with a garbage bag when an officer tried to question him. Crute's lawsuit says the sandwiches were fair game after the vendor tossed.