docker-compose run with isolated sets of services?

I have the following setup:

db:
  image: postgres:latest

app:
  ...
  links:
    - db

When I try to run docker-compose run app testcommand twice, it reuses the db container. Is it possible to make app create another db container?

What I'm after is:

• app_run_1 ---> db_1
• app_run_2 ---> db_2

I'm trying to isolate the services in order to run tests concurrently.