The hash is dynamic and reproduced everytime:

• the user attemps to create an invitation link
• for every email adress that is invited through email

records are on sys_keys and bx_inv_invites tables 

in bx_inv_invites table only the lastest new user's ids are updated with the icode that we sent to many users.

the interesting thing is if you use an hash code for many new users it works, the procedures of befriending both parties and registering points are working for every new user that comes even with the same hashcode.