The EMPLID on PeopleSoft HCM is the Account ID schema flag and is the only value being correlated. However multiple accounts from the view correlate to one identity even though their EMPLID is unique.
I have tried an un-optimized aggregation. I have tried deleting the accounts in ISC and then the identity and re-aggregating. We have 4 unique persons with the same name, but it wants to associate each of the 4 accounts to one identity. Why?
The account name flag on the schema is associated to a name column where that value is the same, but it is not part of the correlation. I also hear that it can be very bad to change that flag to something else.
Yes, i also had the same issue happened and it turned out that there is hidden feature in ISC for correlation where it automatically correlate the accounts to the identity when their display name are same. I believe that is what happening in your case too.
Unfortunately i do not think we can overwrite this correlation logic as it is inbuilt correlation logic admins can not control but you may try to change the schema of the source and change the name attribute (will recommend doing so only if the source is n the non-prod tenant as it may have some implications and should be tested properly) . But the default correlation behavior on display name is also documented in the link below
