Hi Thierry, if you leave ID_ORIGIN or ID empty during CSV upload, the system will generate ID automatically. Hence, the match is happening only by email or phone no.
For example, if you upload following two interactions which doesn't have email address ( l left it blank deliberately), then this will create 2 interactions but 1 contact because it matches by ORIGIN_ID and ID.
SAP_CRM_BUPA;1001;WEB;WEBSITE_REGISTRATION;20150205124748;BIG_DATA;;;;5;;;;;;;;;;www.clickstreamer.com/websession-id=01234;;;bha Doe;bha;Doe;;;;X;;X;X;X;4;4;Sample text;Sample text;123456.12;Sample text;Sample text;Sample text SAP_CRM_BUPA;1001;WEB;WEBSITE_REGISTRATION;20150205124750;BIG_DATA;;;;5;;;;;;;;;;www.clickstreamer.com/websession-id=01234;;;bha Doe;bha;Doe;;;;X;;X;X;X;4;4;Sample text;Sample text;123456.12;Sample text;Sample text;Sample text