# OPF-060: duplicate file names in ZIP, how to fix it

Source: https://epubcc.com/epubcheck/opf-060/ (updated 2026-11-04)

EPUBCheck OPF-060 is an error message: “Duplicate entry in the ZIP file: "…" (file names must be unique after Unicode canonical normalization and full case folding).” Two files in the ZIP have names that are the same once case and Unicode normalisation are ignored, such as Image.jpg and image.jpg. EPUB requires file names to stay unique under those rules.

- Official message (EPUBCheck 5.4.0): Duplicate entry in the ZIP file: "%1$s" (file names must be unique after Unicode canonical normalization and full case folding).
- Default severity: Error

## Typical causes

- Files added on a case-sensitive system that a case-insensitive one would treat as the same file.
- The same file added twice under different spellings, for example with composed and decomposed accents.
- Two versions of an image kept side by side after editing.

## How to fix it

1. Read the file name EPUBCheck quotes.
2. Rename or delete one of the two files.
3. After renaming, update every reference to the file: the manifest in the package document, links and image sources in the XHTML, and url() references in the CSS.

## When it's not this

If the same file is declared twice in the manifest, that is OPF-074.

## Sources

- EPUB 3.3, §4.2.3 File paths and file names: https://www.w3.org/TR/epub-33/#sec-container-filenames (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.