How to get unique identifier from instance and reuse using getInstance()

PDF.js Express Viewer 8.2.0

Detailed description of issue
Is it possible to get a unique identifier of the instance that has been created, so that it can be retrieved agin through getInstance() method? I’m using Vue and running into an issue where the pdfViewer is in a child component and the WebViewer gets initialised every time the component is mounted and when using the getInstance() method it throws the error:

“More than one instance of WebViewer was found, and no element was passed into getInstance(). Please specify which instance you want to get.”

Expected behaviour
I would like to use getInstance() with a unique identifier, so that I can check if that instance is present when my component is mounted, before initialising a new instance. That would also avoid having more than one instance active.

Does your issue happen with every document, or just one?
All documents - general issue.

Code snippet
Something like this, where I get my unique reference from the vue store and then check if that is present, and fetching that instance instead of creating a new one.

mounted: function () {
    const inst = this.$store.getters["pdfviewer/getInstance"];
    if (inst) {
      const {UI} = getInstance(inst);
      UI.loadDocument(this.url, {extension: 'pdf'});
    } else {
        path: '/webviewer',
        licenseKey: 'xxxxKey',
        initialDoc: this.url,
        disabledElements: [
      }, this.$refs.viewer).then((instance) => {
        const {Core, UI} = instance;
        this.$store.commit("pdfviewer/setInstance", instanceRef?);