[mat-tab-group] matTabContent gets duplicated when switching tabs

[hneuer]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Each tab's content should be displayed just once

What is the current behavior?

Some tab's content gets duplicated when the tabs are switched frequently.

What are the steps to reproduce?

• open this StackBlitz: https://stackblitz.com/edit/angular-q2pkcy?file=app/tab-group-lazy-loaded-example.html
• switch fast (i.e. before the animation ends) between the three tabs (in the order Third, First, Second). At some point the content of one of the tabs will be duplicated:

Note: I could reproduce this only with a div element right under the ng-template. It was not reproducible with just the text in there as it is in the original StackBlitz

What is the use-case or motivation for changing an existing behavior?

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Material 7.2.1
Chrome (maybe others)

[Ploppy3]

Yes, it only seems to happen when the content is lazily loaded.

[manklu]

Possible duplicate of #10938
Possibly related to angular/angular#26133

[andrewseguin]

Thanks for reporting the issue, will close as a duplicate of #10938

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