How does CI_COMMIT_TAG get populated when multiple tags on a commit?

I am looking to figure out how CI_COMMIT_TAG is populated. I have a repository scheme where I will need to have multiple tags on a single commit. On top of that, I want to only trigger the pipeline for a specific RegExp for the CI/CD pipeline.

The following is my workflow rules…

workflow:
  rules:
    # Only run the workflow if it matches a valid branch/tag pattern
    # Tag: 1.2.3
    - if: $CI_COMMIT_TAG =~ /^\d+\.\d+\.\d+$/
      when: always
    - if: $CI_COMMIT_BRANCH =~ '/^develop|master$/'
      when: always
    - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
      when: always
    - when: never

I want to be able to tag a single commit with multiple tags. Example: Tag1 - 1.0.2 Tag2 - zealous.mustard.

When I do this today, I get two pipeline runs, once for tagging with 1.0.2 and once for tagging with zealous.mustard. The zealous.mustard tag is added second. How can I prevent a pipeline from running when the second tag is added of zealous.mustard?

Thanks.