angular-cn/aio/content/errors/NG0300.md

@name Selector Collision
@category runtime
@videoUrl https://www.youtube.com/embed/z_3Z5mOm59I
@shortDescription Multiple components match with the same tagname

@description
Two or more components use the same [element selector](guide/component-overview#specifying-a-components-css-selector). Because there can only be a single component associated with an element, selectors must be unique strings to prevent ambiguity for Angular.

@debugging
Use the element name from the error message to search for places where you’re using the same [selector declaration](guide/architecture-components) in your codebase:

```typescript
@Component({
  selector: 'YOUR_STRING',
  ...
})
```

Ensure that each component has a unique CSS selector. This will guarantee that Angular renders the component you expect.

If you’re having trouble finding multiple components with this selector tag name, check for components from imported component libraries, such as Angular Material. Make sure you're following the [best practices](guide/styleguide#component-selectors) for your selectors to prevent collisions.