Subject cannot join multiple COs

cm_cmp_enrollment_configurations.pool_org_identities (Pool Organizational Identities) is FALSE

2 COs, each which self enrollment flows, basically identical. Details attached.

Subject complete enrollment form for first CO, confirmed email, and was approved.

Same subject then completed enrollment form for second CO, received email with invitation to confirm, navigated to link, selected 'Accept' link (tab-like button in top-left of content area). Error returned with message 'Identifier <eppn> already in use.'

The petition is left at 'Pending Confirmation'.

Other details, which may or may not be relevant.
Looking at the database, in table cm_identifiers, there is only a single record for the eppn in question, and that has an org_identity_id value. This was a result of the first enrollment. In previous versions of COmanage, there would have been two records for the eppn, one with an org_identity_id value and one with a co_person_id value.