How to name services that are interchangeable

Hi, we have two service names that we're going to alternate when we deploy a new version.

let's say Foo is now used to run production requests and Bar is to be used re-provision with a new version of the code (blue – green deployment).

After Bar is completely deployed/tested/scaled we'll route traffic to Bar and Foo will be used for re-provisioning.

​

So you can see why we can't name them blue-green (because blue should mean it's the one in production always), nor can we let them named as Foo-Bar since that gives the impression these services are dummies.

​

Any suggestions on how to name these two alternating services?