Storybook + Angular CSF Stories causes 'Multiple defintions' error in IE11

[endlist]

Describe the bug
I had been writing simple MDX stories with Angular, but when I started to try to write more complex stories I found it easier to switch to CSF format. Doing so seems to break IE11, though, so the entire Storybook instance fails to load with the sidebar remaining the grey loader boxes and the main window spinning a loader. If the console was open on load or opened and refreshed you'll notice an error Multiple definitions of a property not allowed in strict mode

To Reproduce
Going to either the current or next Angular examples using IE11 (https://next--storybookjs.netlify.app/angular-cli or https://storybookjs.netlify.app/angular-cli/) has the same behavior.

Expected behavior
No error, the page loads successfully.

Screenshots

Code snippets
An example of how I'm setting up the component in case that's the issue:

// example.component.ts
import { Component } from '@angular/core';

@Component({
  selector: 'lib-example',
  styleUrls: ['./example.component.scss'],
  template: `<div>I do something</div>`
})
export class LibExampleComponent {
  constructor() {}
}

// example.component.stories.ts
import { ExampleComponent } from './example.component';
import { moduleMetadata } from '@storybook/angular';

export default {
  title: 'Components/Example',
  component: ExampleComponent,
  decorators: [
    moduleMetadata({
      declarations: [ExampleComponent]
    })
  ]
}

export const testStory = () => {
  return {
    template: `<lib-example></lib-example>`
  }
}

System:
Please paste the results of npx -p @storybook/cli@next sb info here.

The above command keeps failing with a DeprecationWarning about unhandled promise rejections for some reason, but I'm running @storybook/angular at 5.3.19, MacOS Mojave, Node 10.16.2, npm v6.14.6, and as noted above this seems to be happening on version 6 also if the live Angular examples are up to date.

[shilman]

Try upgrading to 6.0 RC?

npx sb@next upgrade --prerelease

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[ndelangen]

Storybook 7.0 won't support IE11 anymore.

6.5 won't receive updates other than critical security issues, this won't get fixed.