## TL;DR

A metadata label collides with an existing one. Rename the label (or the existing component) so it is unique, then deploy again.

## Error

```text
DUPLICATE_MASTER_LABEL: duplicate value found: [Label] in metadata
```

## Steps

1. Find the existing component with the same label Expected: you see the collision.
2. Rename your component's label Expected: it is unique.
3. Redeploy Expected: it succeeds.
4. Adopt a naming prefix for generated components Expected: collisions stop.

## When to use

- DUPLICATE_MASTER_LABEL on deploy
- Two components share a label

## When not to use

- The labels differ (then check API names too)
- It is a managed package conflict (then contact the vendor)

## Tool compatibility

- Salesforce metadata deploys
- CI/CD for Salesforce

## Variant phrasings

### duplicate master label

Rename the label; it must be unique.

### DUPLICATE_MASTER_LABEL

Same: find the collision and rename.

## Why it happens

Labels must be unique per metadata type, which surprises agents used to duplicate display names elsewhere.

## Edge cases

- API names have their own uniqueness rules; check both
- Deletes of the old component can leave the label reserved briefly

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_97Qz-VLUvUuVhqqAxuOvdg