---
title: 5.2 Duplicate Module ID Detected
permalink: 5-reference/module-duplicate-id
publish: true
visibility: public
tags:
  - manual
garden-url: https://francisfontaine.com/5-reference/module-duplicate-id
garden-short: https://stnd.gd/8CJzgH
created: 2026-07-29T19:39:12.627Z
modified: 2026-08-06T21:40:51.961Z
---

# Duplicate Module ID Detected

> **Error:** `Duplicate module ID "my-id" detected.`

## The Problem

Two different module files are trying to claim the same `id`.

## The Why

Module IDs must be globally unique within your application. The system uses the ID to resolve dependencies and merge configurations. If two modules have the same ID, the system cannot determine which one to use, leading to unpredictable behavior.

## The Solution

1. **Rename one of the IDs:** Change the `id` property in one of the conflicting `index.module.js` files.
2. **Check for Copy-Paste Errors:** Often this happens when you copy an existing module to create a new one and forget to update the ID.