On Premise - Shared same primary data source between 2 Appian servers

I have a primary data source schema, mapped to a Linux dev(ex: dev01) environment. From another Linux server(ex: dev02). I installed new Appian and provided same primary & secondary data source in tomcatResources.xml and custom.properties. dev02 works fine when started. 

This seems to be multi-gateway installation but we are not trying to setup distributed environment. The purpose to do this is to have a separate Appian installation instance where we can do some POCs for upgrade.

Q1. How Appian differentiates same primary data source for these two servers?  

Q2. Will there be any impact on dev01 if we shutdown dev02 and don't use it anymore?

Thanks in advance.