The following error is shown during upgrade precheck to OA 7.0:
Precheck error: There are users with duplicate logins in BA database. Do the following: Fix duplicate logins as described in the Knowledgebase Article #129071 (https://kb.cloudblue.com/129071).
Starting from OA version 7.0, users with logins that differ only in the case of letters are not allowed in BA database. Such inconsistency must be resolved prior to upgrade.
Contact your Technical Account Manager or a member of Pooled Technical Associate team at firstname.lastname@example.org for clarification regarding a possible way to resolve this issue.