What is a cost-effective method of holding two identical versions in memory without excessive copying?

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One cost-effective method of holding two identical versions in memory without excessive copying is by using pointers. Pointers are variables that hold the memory address of another variable. Both variables can point to the same memory location, allowing the identical versions to be stored in the same memory space. This method saves memory and reduces the need for excessive copying. Any changes made to one variable will also be reflected in the other variable.