Several requests point to allowing any number of CAS/LDAP/Google endpoints being configured:

• Scott at capilanou.ca has 2 LDAP search bases (ou=students, ou=faculty) that he wants to authenticate against. We could adjust the ldap_search() filters, or just allow multiple LDAP endpoints to be defined.
• tkilcommons requests 2 Google Apps domains (sub.uni.ac.uk and uni.ac.uk). Note that multiple Google endpoints will result in multiple Google login buttons.
  https://wordpress.org/support/topic/two-approved-google-apps-domains/
• jwillis84 requests 2 CAS endpoints. Note that multiple CAS endpoints will result in multiple CAS buttons.
  https://wordpress.org/support/topic/support-for-alternate-cas-sources-cas1-or-cas2-by-user/#post-8174505