Angular 5 - "Error: Cannot activate an already activated outlet" when named outlets are used in children

I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior

As stated here on stackoverflow when you have a routing configuration like:

export const routes = [
{
    path: '',
    component: IndexComponent, 
    children: [
        {
            path: 'home',
            children: [
                { path: '', component: FirstComponent, outlet: 'first', data: { state: 'a' } },
                { path: '', component: SecondComponent, outlet: 'second', data: { state: 'b' } }
            ]
        },
        {
            path: 'about', 
            children: [
                { path: '', component: FirstComponent, outlet: 'first', data: { state: 'b' } },
                { path: '', component: SecondComponent, outlet: 'second', data: { state: 'a' } }
            ]
        }
    ]
}

And you are navigating from /home to /about using a link <a routerLink="['/about']">about</a> it throws the following error:

ERROR Error: Uncaught (in promise): Error: Cannot activate an already activated outlet
Error: Cannot activate an already activated outlet

Expected behavior

The expected behavior would be that it navigates to /about and the router populates the named outlets with the new components (taking internally care of deactivation/activation of outlets).

Minimal reproduction of the problem with instructions

Just a simple app, with routing a named outlets with the configuration above.

What is the motivation / use case for changing the behavior?

It’s a show stopper.

Environment

Angular version: 5.0.3


Browser:
- [x] Chrome (desktop) version XX
- [x] Chrome (Android) version XX
- [x] Chrome (iOS) version XX
- [x] Firefox version XX
- [x] Safari (desktop) version XX
- [x] Safari (iOS) version XX
- [x] IE version XX
- [x] Edge version XX
 
Others: