Lightroom does not normally support saving multiple sidecar XMP files for one image, and virtual copies are primarily catalog-based. A single image won’t get separate standard XMP sidecars for each virtual copy.

Workarounds mentioned:

• Use snapshots instead of virtual copies. Make one edit, save a snapshot in Develop, then create another look and save that too. Snapshots can be written into the metadata.
• One answer notes that if you save snapshots on the original and virtual copy, then use “Save Metadata to File,” the XMP may contain both snapshots/settings entries, which can preserve both versions.
• Export virtual copies as original/DNG files so each version becomes its own real file with its own metadata. You can rename them and stack them with the original if needed.
• Another simple option is to create a DNG copy after finishing one version, giving you two separate files to edit independently.

So: virtual copies themselves are not truly portable outside the catalog, but snapshots or exporting separate files are the main ways to preserve alternate edits.