The script id determines the sheet. Assuming the credentials are the same, you repeat the step:

- id: configure-clasp

name: gcr.io/cloud-builders/gcloud

entrypoint: 'bash'

args: ['-c', 'echo {\"scriptId\":\"${_SCRIPT_ID}\"} > .clasp.json' ]

with the script id of each sheet, and repeat the push step.