# EPUBCheck OPF-060: Duplicate entry in the ZIP file: …

Source: https://epublab.com/epubcheck/opf-060/ (updated 2026-11-03)

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.

- 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, or the same file added twice under different spellings.

## How to fix it

- Rename or delete one of the two files.
- 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.

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