All recent Koha docs indicate that "A duplicate patron is detected IF first AND last names match AND there is NO date of birth populated OR IF first name, last name AND date of birth fields are ALL populated." (quote from https://koha-community.org/manual/18.11/en/html/patrons.html) This used to be true until Jul 2016. See: https://github.com/Koha-Community/Koha/commit/1c61729e840655bfea7123d0c826a0cffa9bd1bc After that commit, the logic that is described in the docs is no longer true. The newer code looks prettier (and simpler), but I liked the old 'logic'. More specifically, I would like to ALSO have a duplicate warning on firstname+lastname (and Initials maybe?) match, IF the dateofbirth is blank. If -for any reason- the community prefers to only check for firstname+lastname+dateofbirth, please consider updating the docs accordingly :)
Needs more testing! The behavior described might not be accurate. [apologies]