How to create a server which can service multiple entities at the same time?

I want to know how to create a single server system, where the single server can process more than one entity at a time, but with each entity having the same processing time. In some sense, I want to simulate the processing of entities that are on a conveyor belt and enter a machine to undergo some kind of processing, but at any time more than one entity can be processes in this machine

Note that this is different from creating a N-server system because, in the system that I want to simulate, multiple entities cannot exit the systems at the same time, but they can exit the system one after the other only after a specific delay. But in a N-server system, multiple entities can enter the N-server system at the same time and exit at the same time.

Is this possible?