CoreModule has already been loaded. You should only import Core modules in the AppModule only

Im getting this error but I don't know why, since this core module is being imported only once

The code App.Module

  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    HttpClientModule,
    AppRoutingModule,
    SharedModule,
    CoreModule
    ],
  providers: [
    DataService, 
    AuthService,
    ShoppingCartService,
    ProductService,
    HttpClientModule

The appRouting:

const adminModule = ()=> import('./admin/admin.module').then(m=>m.AdminModule);
const coreModule = ()=> import('./core/core.module').then(c=>c.CoreModule);

const routes: Routes = [
  {
    path: '', component:ShellComponent,
    children: [
      {path: 'detail/:id', component: DetailComponent},
      {path: 'admin', loadChildren:adminModule},
      {path: 'home', loadChildren:coreModule},
    ]
  },
  {path: 'login', component: LoginComponent},
  {path:'edit/:id', component:RegisterComponent},
  {path:'register', component: RegisterComponent} 
];

I get this error when I navigate to home page, as I have this constructor in the core module

@NgModule({
  declarations: [
    MoviesComponent,
    DetailNoRoutingComponent,
    HomeComponent,
    ProductCardComponent,
    ProductFilterComponent
  ],
  imports: [
    SharedModule,
    coreRoutingModule
  ]
})
export class CoreModule { 

  constructor( @Optional() @SkipSelf() parentModule: CoreModule) {
    if (parentModule) {
      throw new Error('CoreModule has already been loaded. You should only import Core modules in the AppModule only.');
    }
  }

Can anyone help me out? Im not understanding whats goin on, maybe something Im missing in the imports or the logic is messed up