If a *.env file defines a parameter twice, then it will fail onboarding into SDC

Example:

parameters:   svc_flavor: flavor_name
  svc_flavor: flavor_name

VVP performs a check for duplicate keys in test_initial_configuration::test_02_no_duplicate_keys_in_file, but this only checks YAML files - not .env file.

We either need a new test to check env files or the existing test should be updated to include env files.