After using multiple drawer inside a mat-drawer-container the backdrop is disabled & drawer opening one upon the other. Below is the structure.
<mat-drawer-container autosize (backdropClick)="closeSidenav()" >
<mat-drawer #globalSearch [class.side-drawer]="!searchService.drawerWidth" position="end" disableClose [class.full-drawer]="searchService.drawerWidth">
<app-global-search></app-global-search>
<app-global-bookmark ></app-global-bookmark>
<router-outlet></router-outlet>
</mat-drawer>
<mat-drawer #globalbookmark [class.side-drawer]="!bookmarkService.sidenavWidth" position="end" disableClose [class.full-drawer]="bookmarkService.sidenavWidth">
<app-global-bookmark></app-global-bookmark>
<router-outlet></router-outlet>
</mat-drawer>
<mat-drawer-content>
<router-outlet></router-outlet>
</mat-drawer-content>
</mat-drawer-container>