# `type.copy_clash`

Copied field would replace another field.

Area 2, [Values and types](../topics/values-and-types.md); not declinable; the next step is usually the agent's.

```jadpo
type TodoView = Output {
    pick: [Todo.id, Todo.title, Note.title]
}
```

```text
error: `title` is already in `TodoView`, from `Todo`
 --> main.jadpo:2:33
  |
2 |     pick: [Todo.id, Todo.title, Note.title]
  |                                 ^^^^^^^^^^ copied again
  reason: A copied field never replaces another field, because a field added to a source type would then change this type unseen.
  next: Remove `title` from one of them with `omit: [...]`, or write `title` as a field below them (agent)
  rule: type.copy_clash
  help: https://jadpo.dev/docs/errors/type.copy_clash

check failed: 1 error, 2 files
```