# TS2300: Duplicate identifier '…'.

> The same name is declared twice in one scope in a way that can't merge, such as two properties or two classes. Rename or remove one.

## What it means

Some declarations can merge (interfaces with interfaces, namespaces with classes). Others
can't, and declaring the same name twice in the same scope is reported at each declaration:
two classes, two type aliases, two members with the same name in an interface or class.

## Example

```ts
export interface User {
  id: string;
  id: string;
}
```

## How to fix

- Remove or rename one declaration.
- For block-scoped variables (`let`/`const`) the error is TS2451 instead.

Source: https://ts-r.dev/errors/TS2300/