@aagk123 - That might be possible. Unique Visitors are identified using different identification methods in Analytics - MID, s_vi/AID, custom visitor ID, etc. So, when visitor ID changes even though the user is logged in with the same customer ID, the reports will show multiple Unique Visitors.
Another common reason is to use multiple devices, browsers, etc. - if the same customer is logged into different devices, browsers, Analytics would, by default, treat them as different visitors (unless you are identifying visitors using s.visitorID).
Hope this explains!