I think there is not a problem using multiple kinds of UUIDs in the same system; they will not interfere with each other, because the UUIDs are necessarily different.
Another possibility is to use URIs; UUIDs are URIs too! (Put "urn:uuid:" at front to make a UUID into a URI.)
Another possibility is to use URIs; UUIDs are URIs too! (Put "urn:uuid:" at front to make a UUID into a URI.)