While still editing the pedigree, multiple patients can get the same external identifier and the duplication will not be detected and reported (because the patients are not yet saved, and the CheckID page can only look in the existing patients). On top of the serverside duplication check, the pedigree code itself should look at other patients in the pedigree.
, do you confirm we need this?
, if I understand this issue correctly - yes we do. We cannot have loops holes where duplicate patient records can be created.