It is intentional that more than one record can exist in OA_MEMBERPROFILE table when visitorModelEnabled is turned on. However,
Looking at wsadmin commands to manage user data, they use the EXID or the e-mail.
First field is EXID and second is MEMBERID.
480e9e40-92a9-1034-9ccb-a36c523f0b12 06e3a4c9-67b2-4c29-9d4c-576a5b59c5b9 xxx xxxxx email@example.com 0 1 en-us 10/19/2015 12:47:12.123000 PM 8/8/2017 9:57:58.266000 AM 0 000000000000000000000000000000000004 0 firstname.lastname@example.org xxxx0-xxxx 0 -Ignore-Organization-ID-
480e9e40-92a9-1034-9ccb-a36c523f0b12 36b64563-7ee2-400b-9a94-b7f29f46b996 xxxxx xxxx email@example.com 0 1 3/30/2018 1:52:47.753000 PM
It looks like this intentional design feature breaks the wsadmin commands. Unless you know the wsadmin commands will work with two records like the above.