Using two Keycloak instances as OmniAuth providers

I would like to use two different Keycloak instances as identity providers to login to my self-hosted GitLab. What I tried in the gitlab.rb is this:

gitlab_rails['omniauth_providers'] = [
  {
    "name" => "saml",
    "label" => "keycloak1",
    "args" => {
        assertion_consumer_service_url: "url1",
        idp_cert_fingerprint: "fingerprint1",
        idp_sso_target_url: "url1",
        issuer: "client-in-keycloak1",
        }
  },
  {
    "name" => "saml",
    "label" => "keycloak2",
    "groups_attribute" => "roles",
    "external_groups" => "external",
    "args" => {
        assertion_consumer_service_url: "url2",
        idp_cert_fingerprint: "fingerprint2",
        idp_sso_target_url: "url2",
        issuer: "client-in-keycloak2",
        }
  }
]

But only the first entry shows up on the login page.

Is a setup like this possible, and if yes, how can I get there? Thank you!