If you want every instance of a server to receive the message, then you need to use separate subscriptions. There are two forms of having multiple subscribers:

1. Single subscription, multiple subscribers: this is load balancing, where messages are delivered to one of the subscribers (though duplicates can happen on occasion as Google Cloud Pub/Sub has at-least-once delivery). Use this mechanism when you need multiple subscribers to handle the throughput of messages.
2. Multiple subscriptions, one subscriber per subscription: this is fan out, where messages are delivered to all of the subscribers because they each have their own subscription. Use this mechanism when you need each subscriber to receive and process every message.