Multiple cluster namespace tenancy

I’m testing the multiple cluster setup with replicated control planes as per this documentation:

And on the whole it seems to work fine over 2 clusters. I can reach services in the other clusters either directly from the sidecar or through the egress gateway when I setup the .global serviceentry.

I am however confused by the documentation here around namespace tenancy:

Particularly the paragraph:

When using multiple clusters, the namespaces in each cluster sharing the same name are considered the same namespace. For example, Service B in the foo namespace of cluster-1 and Service B in the foo namespace of cluster-2 refer to the same service, and Istio merges their endpoints for service discovery and load balancing.

What does this mean (I can’t find any further documentation or examples on this) and how can it be achieved? Or is this actually referring to using the service entry as demonstrated in the multicluster setup documentation?