Duplicate files are identical copies of data stored in multiple locations, consuming storage capacity without adding value. They accumulate through manual duplication, backup processes, or application actions. Each duplicate consumes the same space as the original, directly reducing the amount of free space available. While seemingly insignificant individually, their collective volume becomes substantial over time.

For instance, users often unknowingly save multiple copies of the same photo, document, or media file in different folders on their personal computers or mobile devices. In business environments, duplicate project files (like presentations or spreadsheets) emailed between team members or saved to shared drives and local machines are common. Storage systems and backup servers frequently retain versions or copies that become redundant over time.

This wasted space leads to higher storage costs as more hardware may be needed prematurely. System performance suffers during backups, scans, or indexing as software processes redundant data. Locating the correct file becomes harder. Deduplication tools or careful data management practices help mitigate this by identifying and removing unnecessary copies, freeing up significant space.