distributed systems – need for an example for a layman of linearizable coherence model

For all I know,

The lineariable coherence model is a Data centric and strong consistency model.

Data centric means:
– All customers experience the consistency
– All clients access the same data store
– All customers are subject to the same order
– Non-mobile customers. That is to say. replica used does not change. That is to say. replicas are not affected by synchronization delays.

Strong means:
– Operations on shared data are synchronized

this link has a good and easy to follow example. But, I'm confused on one thing.

In the first image,
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it only shows one data store.

But, in the second picture,

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it shows two data stores.

Why is that?

Is not it possible to show the example with only one data store in the second case?