1. A system for copying files or data objects from a computer system at a first location to a second location, including single-instancing the files or data objects with a plurality of differing associated metadata, the system comprising: a processor; and multiple hardware components, including: a storage operation manager component coupled to the processor and configured to receive a request to copy a file or data object from a computer system at a first location to a second location, wherein the first location and the second location are geographically remote from each other; a file cache component at the first location configured to: receive the file or data object to be copied from the computer system, and store the file or data object before it is copied to the second location; a single instance database component at the first location configured to: extract metadata associated with the file or data object, query the second location to determine whether the file or data object is already stored at the second location, wherein the query includes the extracted metadata, and receive a response from the second location that indicates whether the file or data object is already stored at the second location, wherein the response is based on determining at the second location whether the extracted metadata matches metadata from any files or data objects stored at the second location; and wherein the single instance database component at the first location is further configured to: when the file or data object is not already stored at the second location, copy the file or data object from the file cache component at the first location to the second location, and when the file or data object is already stored at the second location and the extracted metadata does not match metadata stored at the second location, (a) single-instance the file or data object at the second location by declining to copy the file or data object thereto from the file cache component at the first location, and (b) copy the extracted metadata to the second location and associate the extracted metadata with the already-stored file or data object at the second location, thereby storing for a single stored instance of the file or data object at the second location at least a first metadata version and a second metadata version that is different from the first metadata version.