`export { _void as void }` leads to exporting duplicate identifiers

### 🔎 Search Terms

`export void` `export reserved` `export null`

### 🕗 Version & Regression Information

- Reproducible since typescript v4. In older releases, it doesn't export anything. I also tried the latest dev release (5.9.0-dev.20250716)
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about `exports`

### ⏯ Playground Link

[Playground (important: lang:javascript)](https://www.typescriptlang.org/play/?target=99&jsx=0&filetype=js#code/FAUwHgDg9gTgLgAgMZQHYGdEH0BuUCWAJggLwIDeAvsKJLIuQrgcQIboJ5EKUI1A)

### 💻 Code
Using the following `tsconfig.json`:

```json
{
"compilerOptions": {
"target": "esnext",
"lib": ["esnext"],
"module": "esnext",
"allowJs": true,
"checkJs": true,
"declaration": true,
"declarationMap": true,
"outDir": "./dist",
"emitDeclarationOnly": true,
"strict": true,
"noImplicitAny": true,
"moduleResolution": "bundler"
}
}
```

I compile declaration files for this code `${project}/schema.js` (only happens when compiling javascript):

```ts
const _null = {}
const $void = {}

export { _null as null, $void as void }
```

### 🙁 Actual behavior

The produced declaration file `schema.d.ts` is erroneous. It has duplicate identifiers:

```ts
declare const _null: {};
declare const $void: {};
export { _null as null, _null as null, $void as void, _void as void };
```

### 🙂 Expected behavior

No duplicate identifiers:

```ts
declare const _null: {};
declare const $void: {};
export { _null as null, $void as void };
```

### Additional information about the issue

For any reserved keyword, `tsc` always exports `_{reserved} as {reserved}`, whenever `{reserved}` is exported. Even though the variable `_{reserved}` does not exist.

It is only reproducible when compiling javascript.

Commencez par le tsconfig.json fourni et la reproduction de schema.js, puis examinez l’émission de déclarations uniquement de JavaScript pour la liste des exports. Comparez le schema.d.ts généré aux instructions d’export attendues ; c’est terminé lorsque les exports de mots-clés réservés apparaissent une seule fois et qu’aucun identifiant inexistant n’est émis.

Rédigé par le modèle d'indexation à partir du texte de l'issue.