Duplicate files are defined by identical content, not filenames. If two files contain the exact same sequence of bytes – meaning every letter, number, symbol, and piece of data matches perfectly – they are duplicates, regardless of their file names. Filenames are simply labels assigned by users or systems to identify and organize files; they don't alter the underlying data contained within the file. Therefore, differing names alone do not prevent two files from being duplicates if the actual content is identical.

In software development, version control systems like Git treat files as identical for tracking changes based solely on their content hash (a digital fingerprint), ignoring the filename. Data deduplication technologies in backup systems and cloud storage also identify identical files by analyzing their content to save storage space, often renaming duplicates without regard to the original filenames during the optimization process.

Identifying duplicates purely by content offers significant storage efficiency advantages. However, a key limitation is that files might represent the same logical information (like the same document) but be stored in different formats (e.g., DOCX vs. PDF), have slightly different metadata, or use varying encoding. Content-based identification would not recognize these as duplicates despite the functional equivalence. This approach prioritizes technical precision over the user's intent regarding file organization and naming.