Google App Engine does not deploy two services (seem to be overriding each other)

I have a Django backend and an Angular frontend and i'm trying to deploy both of them to a Google App Engine Standard app as two services within the same app.

The directory looks like this:

-backend
--cloudbuild.yaml
--app.yaml
-- ...
-frontend
--cloudbuild.yaml
--app.yaml
-- ...
-cloudbuild.yaml

The main cloudbuild.yaml goes through each folder and looks for a cloudbuild.yaml file and submits the build:

steps:
- name: 'gcr.io/cloud-builders/gcloud'
  entrypoint: 'bash'
  args:
  - '-c'
  - |
    for d in */; do
      config="${d}cloudbuild.yaml"
      if [[ ! -f "${config}" ]]; then
        continue
      fi

      echo "Building $d ... "
      (
        gcloud builds submit $d --config=${config}
      ) &
    done
    wait

When i push the code to my Github repo, they get deployed successfully. However, both logs show something like below:

Step #2: Beginning deployment of service [default]...
Step #2: #============================================================#
Step #2: #= Uploading 0 files to Google Cloud Storage =#
Step #2: #============================================================#
Step #2: File upload done.
Step #2: Updating service [default]...
Step #2: ................................done.
Step #2: Setting traffic split for service [default]...
Step #2: .....done.
Step #2: Deployed service [default] to [https://thisapp.appspot.com]

So it seems like one is overriding the other as the default service. When I go to the services page, there is only one service which is the default one.

I know that we first have to deploy the default service and then the rest. However i thought since the main cloudbuild.yaml submits the build one by one, then there would be a default service and the second build would create a second service.

The other two cloudbuild.yaml files are as below:

steps:

  # Install node packages
  - name: 'gcr.io/cloud-builders/npm'
    args: [ 'install' ]

  # Build productive files
  - name: 'gcr.io/cloud-builders/npm'
    args: [ 'run', 'build', '--prod']

  # Deploy to google cloud app egnine
  - name: 'gcr.io/cloud-builders/gcloud'
    args: ['app', 'deploy', '--version=prod']

steps:

  - name: 'python:3.7'                                                                                                                               
    entrypoint: python3                                                               
    args: ['-m', 'pip', 'install', '-t', '.', '-r', 'requirements.txt'] 

  - name: 'python:3.7'                                                            
    entrypoint: python3                                                           
    args: ['./manage.py', 'collectstatic', '--noinput']

  - name: 'gcr.io/cloud-builders/gcloud'
    args: ['app', 'deploy', '--version=prod']

I'd be grateful if you can help me on this.

Thanks