When two or more shows share the same pool of writers (or when a freelance scriptwriter is a particular combination of industrious and lazy), it's not unknown for tight deadlines to be handled by the expedient of taking a script already used by one show and "translating" it to another show. Characters are mapped onto their closest equivalents, and situations are revised slightly to fit the new program, but the same plot is used unchanged. A show targeted at a Fleeting Demographic or one that is a sufficiently Long Runner may well unabashedly recycle its own scripts every few years.