When adding a new relationship, the drop-down list used to specify the relationship type shows duplicate list entries (see screenshot).
I've checked the related vocabulary lists: They're fine (no duplicates).
CA providence installed using the included ISAD(G) profile.
OS: Xubuntu 16.04.3 (64bit)
Tested in browsers:
Chromium (Version 63.0.3239.132)
Sorry, the term "vocabulary lists" was not correct
I meant I've checked the relationship type items of "object <=> object relationships".
(In Manage > Administration > Relationship Types)