Multiple User with same login - avoiding session mix up issue
I have a web based application with roughly around 200 users. We have a concept where in two users say A & B are there. User A can login with his login and also User B can login with A's login. This is handled by a "Purge User" concept.
My problem is, because of which,
1) When User A logs in, he gets some session of User C or D ???
I want to keep my "Purge User" concept unchanged, but yet should solve the session mix up.
Please throw some light on the above issue.