1. A method for deduplication in a memory system using data association information, comprising: extracting information about a target file and at least one reference file associated with the target file as association information before duplication determination is performed; identifying the at least one reference file using at least the association information as a comparison target set for comparison; performing the duplication determination with the target file with respect to the at least one reference file in the selected comparison target set; and performing deduplication on the target file and the at least one reference file when the performing of the duplication determination indicates that the target file and the at least one reference file are duplicates, wherein the association information includes an indicia of copying or renaming as metadata of the target file, and wherein the performing the duplication determination comprises: dividing the target file into a plurality of chunks; tagging the association information with respect to each of the divided chunks; and performing the duplication determination with respect to the chunks, with which the association information is tagged, of the reference file in the selected comparison target set using the association information, and wherein when duplication has been determined with respect to each of the chunks, only one copy of the duplicated chunk is stored into the memory system and other copies of the duplicated chunk are replaced with a link to a location within the memory system where the only one copy of the duplicated chunk is stored.