Recently a client called me explaining a “funny” problem they have, they were using SharePoint Online to invite to their external users to collaborate in their platforms, so they were using the Share feature.
The problem begins when they invited two new users to collaborate into their platform. The client sent an invitation to each one of the users, but one of them forwarded the invitation to the other one, and this user registered themselve to the portal with the invitation from the other user (little messy here).
So, what happened?? The user that accept the “forwarded” invitation can enter to SPO, but the account and name are from the original user while the Work Email are from the user that accepts the “forwarded” invitation.
As you can think, the user wants to view displayed his own name, not his colleague name… And also you were thinking, what is happening with the other invitation, the “original”, the user that receives the “forwarded” invitation tried to register again, but he complain that was not possible to accept another time the invitation, I suppose that O365 detects that there is one user with this email, and not accept two users with the same email account.
It wasn’t my tenant but I was guessing that this problem was easy to solve, so I tell to the client that he needs to access to the O365 portal and check into the user in question and try to eliminate from the tenant
Once the user was eliminated, they invited again the two users, and both were able to access to the SPO site.
Hope it helps!
Albandrod's Memory 