It’s possible to run multiple instances of the PostgreSQL service on the same server, but they each have to be on their own port. To register multiple instances of Postgres:
Copy the existing database to a new location for each additional Postgres instance you want to create (you don’t need to copy any other files other than the database – i.e. you do not need to copy the binaries to run the program twice – for clarity, you do not need multiple copies of the exe’s to run multiple instances of Postgres, they all run from the one set of binaries).
Right click the command prompt icon and run it as Administrator
Run the following command, specifying a new port number and different PostgreSQLServiceName for each additional Postgres instance you wish to run: