You may use the share operator on your result from HttpClient.get, like this:
var observable = this.httpClient.get('api/version/secured', { headers: httpHeaders })
.pipe(share());
You’ll need to add the following import on top of your script:
import { share } from 'rxjs/operators';
The share operator makes an observable hot, i.e. shared between subscribers. But there’s a lot more to it, I would suggest this article to dive deeper (you can of course also google up hot vs cold observables to find more).