In GW it is possible to have identical usernames in different POs.
GMS1 did not understand this really simple concept.

GMS2 has changed nothing in this respect (I doubt it will ever).

User 'A' in PO 'Z' has Password '1'.
User 'A' in PO 'Y' has Password '2'.

First time login to GMS2:
I login as user 'A' with Password '1'! (from PO 'Z')
Guess what: GMS shows the information from user 'A' from the PO 'Y'!

I did not check what information actually gets transferred. I had enough...