There may be some constituents in Luminate with duplicate email addresses, if I perform a custom constituent import and use email address as the primary identifier will the import affect all of the records with that email?
No. When you perform an import, Luminate will always assume that one row of data corresponds to one constituent record. If you use only the email address as your identifier in the upload file and that email matches multiple records, the system will choose one record to update (generally the one with the earliest creation date) and ignore any other records. If you would like your updates to apply to multiple records, you will need to have a separate row in the upload file for each constituent. In addition you will need enough extra identifying information to distinguish the constituents, so it is recommended that you also include at least first and last name in the upload file.